language descriptions of the solution. * You are forbidden from using AI to
diagnose or resolve
→ Pay attention
→ Top rated
| # | User | Rating |
|---|---|---|
| 1 | Benq | 3676 |
| 2 | Kevin114514 | 3659 |
| 3 | jiangly | 3640 |
| 4 | turmax | 3450 |
| 5 | tourist | 3408 |
| 6 | strapple | 3360 |
| 7 | Um_nik | 3354 |
| 8 | squareOf105 | 3348 |
| 9 | maroonrk | 3312 |
| 10 | idontwannadothis…e | 3191 |
→ Top contributors
| # | User | Contrib. |
|---|---|---|
| 1 | Qingyu | 154 |
| 2 | nik_exists | 151 |
| 3 | maspy | 149 |
| 4 | AmShZ | 146 |
| 5 | Um_nik | 143 |
| 6 | Errichto | 139 |
| 7 | BledDest | 136 |
| 8 | adamant | 135 |
| 9 | maroonrk | 133 |
| 10 | cry | 130 |
→ Find user
→ Recent actions
You can use several words in query to find by all of them at the same time. In addition, if you are lucky search understands word forms and some synonyms. It supports search by title and author. Examples:
305— search for 305, most probably it will find blogs about the Round 305andrew stankevich contests— search for words "andrew", "stankevich" and "contests" at the same timeuser:mikemirzayanov title:testlib— search containing "testlib" in title by MikeMirzayanov"vk cup"— use quotes to find phrase as istitle:educational— search in title
Results
1.
Rule Restricting the Use of AI [revision 2024-09-14] It seems that neural networks are working technological wonders. Not long ago, they struggled with even the simplest tasks in our competitions, but now they are reaching new heights that cannot be overlooked.
There is reason to believe that progress will continue, and we can expect further advancements in neural networks within the realm of programming competitions.
For this reason, we are explicitly limiting the use of AI-based systems (such as various models like GPT, Gemini, Gemma, Llama, Claude, and others) for solving programming problems.
However, we recognize that AI can be a valuable tool for learning and coding assistance, so we aim to establish clear boundaries for its use.
**Application of this Rule:**<br/>This rule applies strictly to in-contest participation. This includes both registered contestants and out-of-competition participants in any rated Codeforces round. If a round is unrated and this is explicitly stated in the round announcement or rules, the rul...
2.
Polygon: AI-Powered Automatic Tips Hello, Codeforces!
<i>For the new members of the community, I would like to remind you that Polygon (https://polygon.codeforces.com/) is a system developed
and maintained by Codeforces for preparing programming problems. It is there that authors and coordinators develop all the problems for
the rounds. Moreover, I believe a significant (large?) portion of the problems for other competitions is also developed there: various
stages of ICPC, national competitions of different levels, educational problems for various courses, etc.
<b>In 2023, more than 50000 problems were prepared in Polygon (only those for which a package was compiled are counted)!</b></i>
Large language models are becoming an increasingly integral part of our lives, taking over routine and monotonous tasks.
With their help, problems created in Polygon will now have fewer typos and incorrect language constructions.
We have recently implemented three features in Polygon to ease routine tasks:
* Translati...
Polygon (only those for which a package was compiled are counted)! Large
language models are, Large language models are becoming an increasingly integral part of our lives,
taking over routine
3.
April Fools Day Contest 2026 Hello, Codefoolers!
We, [user:AlperenT,2026-03-29], [user:Ari,2026-03-29], [user:ToxicPie9,2026-03-29], [user:flamestorm,2026-03-29], [user:prvocislo,2026-03-29], [user:temporary1,2026-03-29], and [user:willy108,2026-03-29] would like to invite everyone on Codeforces to [contest:2214]! The 14th April Fools Day Contest will take place on [contest_time:2214]. This is a joke competition in which solving the problem is often easier than figuring out what the actual task is.
In this round, you will be given $n$ problems where $n$ is the number of different AI models I used today and **2** hours to solve them. The contest will use extended ICPC rules (no hacks, the standings are decided by the number of solved problems and penalty time earned on them). You can submit solutions in any language allowed by Codeforces, unless the problem says otherwise.
There will be at least one non-interactive problem. In case you do not care about those problems, [here](https://codeforces.me/blog/e...
solutions in any language allowed by Codeforces, unless the problem says
otherwise., language allowed by Codeforces, unless the problem says otherwise. There will
be at least one non
Announcement of April Fools Day Contest 2026
4.
AI has ruined this contest, especially for Div. 1 contestants ### UPD. The rating finally roll back. Cheers
Today’s Global Round 29 felt fundamentally broken. Problem G was tailor-made for language models: a math task where a fluent explanation and a few lines of code could be produced on demand. The result was a scoreboard flooded with sudden G solves from accounts that otherwise struggled, while many honest Div.1 regulars—who actually reasoned through the problem—were pushed down. That isn’t competition; it’s a prompt-engineering race.
The damage is real: unfair rating shifts, polluted editorials, and a growing sense that integrity checks aren’t keeping up—especially when AI can generate proof-like text and lightly paraphrased code that slips past plagiarism filters. If Codeforces wants to protect the competitive spirit, we need tougher post-contest verification (e.g., short solution justifications for late problems), targeted rejudges with hidden variants, stricter accou...
Today’s Global Round 29 felt fundamentally broken. Problem G was tailor-made for
language models: a, language models: a math task where a fluent explanation and a few lines of code
could be produced on
5.
OpenAI Codex can solve unseen Codeforces problems In this post, we will use the recent OpenAI Codex product based on GPT-3, first introduced in [Evaluating Large Language Models Trained on Code (Chen et al., 2021)](https://arxiv.org/abs/2107.03374) to solve some Codeforces problems.
We use the round [contest:1560] because the current version of the Codex model was released before this round. As the model has been trained on the Github data, it is possible that it memorized some solutions for older problems.
### Solving [problem:1560A] from the statement only
This is a simple problem, and the statement kind of explains what we should implement. Let's just give the plaintext statement to Codex:
<spoiler summary="Prompt">
Problem:
Polycarp doesn't like integers that are divisible by 3 or have the last digit 3
in their decimal representation.
Polycarp starts to write out the positive (greater than 0) integers which he likes:
1,2,4,5,7,8,10,11,14,16,….
Output the k-th element of this sequence (the elements are numbered...
[Evaluating Large Language Models Trained on Code (Chen et al.,
2021)](https://arxiv.org/abs/2107.03374, to work on important things, in my opinion language models are very critical
right now., #### Can language models solve harder problems? Language models are a new and
poorly understood, -language-model/), As of 2021, language models are not intended for solving algorithmic puzzles or
producing, GPT-3 is a language model. Its main purpose is translating between different
representations of the
6.
Are we close to machines solving ICPC problems? Hi, all,
I with few other folks at [NEAR](http://near.ai/blog) work on teaching machines to program. A particularly exciting sub-project of that is teaching machines to solve competitive programming problems.
In this post I would like to give a quick overview of where the state of the art is today, what the major challenges are, why this is not a popular area of research, and how the CodeForces community can help to address some of the issues the program synthesis community is facing today.
We also have a certain budged allocated for this project, and we are paying to the CodeForces members who help us with some data annotation challenges. We have paid more than $10k in our first two annotation projects, and are launching three more projects today. Scroll to the end if you are interested.
Competitive programming as a benchmark
======================================
With the emergence of deep learning, neural networks started performing almost at a human level in many ta...
domain-specific language and writing few C# functions. A separate epic paper
from a different lab, trained well. If a model predicts code one token at a time, and a code snipped
comprises 200 tokens
7.
Educational Codeforces Round 143 [Rated for Div. 2] Hello Codeforces!
On [contest_time:1795] [contest:1795] will start.
Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.me/blog/entry/51208">blog post</a>.
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest, you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.
You will be given **6 or 7 problems** and **2 hours** to solve them.
The problems were invented and prepared by Adilbek [user:adedalic,2023-02-15] Dalabaev, Vladimir [user:vovuh,2023-02-15] Petrov, Ivan [user:BledDest,2023-02-15] Androsov, Ma...
assess the quality of the model;_ - _Spanish language proficiency;_
Announcement of Educational Codeforces Round 143 (Rated for Div. 2)
8.
Competitive Programming in the Era of AI **Read the original post on :** https://www.vibhaas.net/posts/Competitive-Programming-in-the-era-of-AI/
<br>
<div align="center">
<img src="/predownloaded/3e/ae/3eaee0e93cf1784ab4923157729c81dd3a080fcf.jpg"
alt="Wanderer above the Sea of Fog, Caspar David Friedrich"
width="70%">
<br>
<small><i>Wanderer above the Sea of Fog, Caspar David Friedrich</i></small>
</div>
<blockquote>
Picture this. You've had a draining week at university or at work. You're exhausted, and you need a break. Most people would play a few video games, grab a few beers with their friends, or just sleep. But you have the (mis?)-fortune of being addicted to this weird, aesthetically questionable website called Codeforces (or AtCoder, or whatever your favorite OJ is).
</blockquote>
<blockquote>
You check the list of upcoming contests, and you're in luck. "Nice," you think to yourself, "two rated contests back to back!" This is going to allow you to farm some rating! ...
release of Large Language Models which can solve an increasing fraction of CP
problems, getting an AC, , competitive programming has (not so) quietly entered a new era. With the
release of LargeLanguage
9.
OCPC 2026 Winter — wrap _If you are potentially interested in participating in OCPC **in person** in Summer/Autumn 2026, **please** fill **[this form](https://forms.gle/VdMRh6cAJRN4YvQN6)**!_
Hi everyone!
<center><a href="https://ocpc.camp"><img src="https://ocpc.camp/images/ocpc_light.svg" height="80px"></a>
<a href="https://icpc.foundation/"><img src="/predownloaded/43/08/43086529a28ccb5c9f2f2eec560ffa85e09c6881.svg" height="80px"></a></center>
<center>
<b>Supported by</b><br>
<a href="https://www.janestreet.com/join-jane-street/open-roles/?type=students-and-new-grads&location=london">
<img src="/predownloaded/ee/f2/eef26616a3661c658d1545f18ed21fabb14d5871.svg" height="40px" style="margin: 10px 10px 10px 10px;"></a>
<a href="https://www.hudsonrivertrading.com/">
<img src="https://ocpc.camp/images/HRT.svg" height="40px" style="margin: 10px 10px 10px 10px;"></a>
<a href="https://www.silares.com/">
<img src="https://ocpc.camp/images/silares-red.svg" height="40px" style="margin: 10px 10px 10px ...
outside your team (and organizers), or with large language models, is _not
allowed_, as we try to, with large language models, is _not allowed_, as we try to replicate the
environment of main official
10.
Educational Codeforces Round 134 [Rated for Div. 2] Hello Codeforces!
On [contest_time:1721] [contest:1721] will start.
Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.me/blog/entry/51208">blog post</a>.
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.
You will be given **6 or 7 problems** and **2 hours** to solve them.
The problems were invented and prepared by Adilbek [user:adedalic,2022-08-26] Dalabaev, Vladimir [user:vovuh,2022-08-26] Petrov, Ivan [user:BledDest,2022-08-26] Androsov, Mak...
Announcement of Educational Codeforces Round 134 (Rated for Div. 2)
11.
Grakn Forces 2020 “Codeforces… assemble!”
<center>
<img alt="grakn" src="https://grakn.ai/assets/svg/logo.svg" style="float:right; height: 50px; margin: 10px; max-width:10%;"/>
</center>
We are thrilled to announce **Grakn Forces 2020**; hosted by Codeforces and sponsored by [Grakn Labs](https://vaticle.com/). Thank you to Codeforces for providing a world-class competition structure to partner with. We can’t wait to see what you all are capable of. This international competition consists of 1 round, lasting 2.5 hours. The contest will comprise 7-9 problems and will be in accordance with classic Codeforces rules.
**Prizes:**
- 1st place = 500 euros
- 2nd place = 250 euros
- 3rd place = 100 euros
**Additional Prizes:**
Top 50 receive:
_Grakn Labs swag pack:_
- Stickers
- Grakn Labs t-shirt
Random 50 from 51-250 receive:
_Grakn Labs swag pack:_
- Stickers
- Grakn Labs t-shirt
**About Grakn Labs**
[Grakn Labs](https://github.com/graknlabs) is a team...
expressive knowledge schema language through an enhanced entity-relationship
model, transactional, knowledge schema language through an enhanced entity-relationship model,
transactional queries that
Announcement of Grakn Forces 2020
12.
AI language models and cheating in online contests Hello, Codeforces!
I am one of the moderators of Luogu, which is the largest competitive programming online judge system and online community in China. We hold online contests frequently.
To emphasize academic integrity, we **run an anti-plagiarism system to catch the cheaters** after every contest.
Traditionally, all cases of cheating are like “person A uses person B’s code and directly submit it in the contest”. But as more and more people are knowing how to use **ChatGPT** or other AI language models, the situation is becoming more and more complex.
Now after every easy enough contest (we also have Div. 3 and Div. 4), those easy problems which are capable for ChatGPT to solve, will contain an amount of AI generated submissions.
I kindly ask other contest-hosting platforms, what’s your solution to this problem? How to deal with these AI generated submissions, should we regard these as cheating and disqualifies the submitters? If so, is there any possibilities that ther...
AI language models and cheating in online contests, AI language models, the situation is becoming more and more complex. Now after
every easy enough, contest”. But as more and more people are knowing how to use **ChatGPT** or
other AIlanguage models
13.
Machine Learning Based Rating Predictor ### TLDR;
I built an enterprise grade machine learning model to predict a user rating 6 months in the future. The model has mean absolute error of 65.15 (that is, $ E \left [ \left | \hat{x} - x \right | \right ] = 65.15 $). You can use it here:
[https://fbrunodr.com/predict-codeforces-rating](https://fbrunodr.com/predict-codeforces-rating)
### Motivation:
Check this thread:
[https://codeforces.me/blog/entry/143626?#comment-1282206](https://codeforces.me/blog/entry/143626?#comment-1282206)
Before going forward with this post I have to admit a pretty important thing: I did not do what I promised, as I did not build a foundational model on top of codeforces data. Reasons:
1. Takes to much time to train on my personal laptop (or money to rent gpus, which I am not willing to expend for a toy project).
2. I still almost went down the path of finetuning some feature extractor model (such as [this one](https://huggingface.co/Qwen/Qwen3-Embedding-0.6B)), but then I r...
serveless to avoid unexpected bills), so running a medium language model there
was not a viable, user order their data by time and train a language model to predict what event
the user will do, ), so running a medium language model there was not a viable option. I also did
not feel like renting
14.
Refact.AI Matches <img src="/predownloaded/11/18/111879e63c0725e4d5f3ad8a35f1c4a37a2f927e.png" style="float:right; margin: 0 0 2em 2em; width:300px;"/>
Hello, Codeforces.
We're Refact.ai, an open-source AI Coding Assistant, and on November 9th, we'll be hosting our first round on Codeforces! It will be a combined Div.1+Div.2 round. Welcome!
The winners will receive valuable prizes, and all participants will have a chance to get some exclusive merch from us.
Refact.ai is pushing AI beyond simple code completion. Soon, we'll launch the Autonomous AI Agent—a developer's buddy that handles real engineering tasks end-to-end, from planning and coding to testing and deployment.
If you're excited about AI in software development and want to build the future instead of focusing on the trivial, join Refact.ai, founded by a former OpenAI researcher. We're looking for talented Researchers and Backend developers to join our team.
We already have competitive programmers on board, such as [user:humbe...
, and much more! Assign tasks in natural language, select from models like
GPT-4o, GPT-4 Turbo, Assign tasks in natural language, select from models like GPT-4o, GPT-4 Turbo,
Claude 3.5 Sonnet
15.
Codeforces Round 1121 (Div. 2) Editorial # Codeforces Round 1121 — Editorial
Thanks for participating!
### [problem:2264A]
Problem by [user:qwexd,2026-09-13].
<spoiler summary="Hint">
Look at the elements that are not in the right position. Which of them must be selected? Can selecting any other element help?
</spoiler>
<spoiler summary="Solution">
Every element that is not in the right position has to be selected; otherwise, it never moves.
Selecting an element that is already in the right position cannot help. For it to stay correct after the reversal, it has to be paired with itself, because its value occurs nowhere else in the permutation. Thus it can only be the middle selected element, and removing it changes nothing.
So, if the array is already sorted, choose any one element. Otherwise, select exactly the misplaced elements and reverse them. The answer is `YES` if this sorts the array, and `NO` otherwise.
If the misplaced positions are listed from left to right, the reversal pairs the...
to $50$, due to the particular restrictions of the Deranged Calculator language
, this limit is quite, to the particular restrictions of the Deranged Calculator language, this limit
is quite tight. So for
Tutorial of Codeforces Round 1121 (Div. 2)
16.
Yandex Cup 2025! Hello Codeforces!
------------
We are pleased to announce the start of the Yandex Cup 2025 Championship!
This year, we still have 6 tracks and a prize fund of 12 million rubles:
- [Algorithm](https://yandex.com/cup/algorithm/)❤️
- [Machine Learning](https://yandex.com/cup/ml/)
- [Backend](https://yandex.com/cup/backend/)
- [Analytics](https://yandex.com/cup/analytics/)
- [Frontend](https://yandex.com/cup/frontend/)
- [Mobile development](https://yandex.com/cup/mobile/)
<center style="margin: 2em;"> <a href="https://yandex.ru/cup/?utm_source=partners&utm_medium=social&utm_campaign=yandex-cup25&utm_term=CodeForces" style="text-decoration: none;font-size: 18.0px;background-color: rgb(255, 232, 28);color: rgb(0, 0, 0);font-weight: bold;padding: 0.5em 1.0em;">REGISTER</a>
</center>
Let's talk in more detail about two directions:
**Algorithm** ❤️
An important change this year: we ask a...
problem illustrations Q&A with VLMs. - Large Language Models hallucinations
robustness, . - Large Language Models hallucinations robustness.
17.
ICPC Challenge powered by Huawei <img src="/predownloaded/af/22/af228fee1abb015217d8c524de74898aeff36419.png" align="right" style="height: 280px;" alt="text"/>
#### Hello, Codeforces!
We are happy to invite you to an exciting online event: **ICPC Online Challenge powered by Huawei**.
#### This Challenge features the problem
Scheduling Algorithm for Collaborative Inference System
With the rapid advancement of artificial intelligence, large language model (LLM) services are becoming increasingly integrated into people’s daily lives and work. At the same time, the economic efficiency and data security of these services are receiving greater attention.
**Edge-Cloud Collaborative Inference** has emerged as a promising approach to addressing these challenges.
In this architecture, LLM inference is divided between a user’s on-premises edge environment and the cloud. Using a U-shaped split, the first and last layers of the model run on the edge, while the computationally intensive middle layers run in the c...
artificial intelligence, large language model (LLM) services are becoming
increasingly integrated into, intelligence, large language model (LLM) services are becoming increasingly
integrated into people’s
18.
Educational Codeforces Round 140 [Rated for Div. 2] Hello Codeforces!
On [contest_time:1767] [contest:1767] will start.
Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.me/blog/entry/51208">blog post</a>.
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.
You will be given **6 or 7 problems** and **2 hours** to solve them.
The problems were invented and prepared by Adilbek [user:adedalic,2022-12-15] Dalabaev, Vladimir [user:vovuh,2022-12-15] Petrov, Ivan [user:BledDest,2022-12-15] Androsov, Mak...
objectively assess the quality of the model;_ - _Spanish language proficiency;_, reproducibility and logging, you can objectively assess the quality of the
model;_ - _Spanish
Announcement of Educational Codeforces Round 140 (Rated for Div. 2)
19.
Llama Code: Open Coding LLM Llama Code in CP
==================
Today, Meta released Llama Code, a Large Language Model trained specifically for code. It's trained on Python, C++, Java, PHP, Typescript, C#, Bash. They are releasing 3 models with 7B, 13B and 34B parameters respectively. The smaller two allow for Fill-in-the-Middle.
It's free for research and commercial use, but obviously requires a solid amount of computing power if you want to run it locally.
You can read more about it here: [https://about.fb.com/news/2023/08/code-llama-ai-for-coding/](https://about.fb.com/news/2023/08/code-llama-ai-for-coding/)
I'd be interested in seeing if this becomes useful in CP. It seems like there's a lot of potential, specifically with code completion with Fill-in-the-middle. Imagine having vscode, hitting "F3", typing something like "SegTree with lazy prop, range set max, and range +=", and getting exactly the segment tree you need in two seconds.
I also think it may be useful because although LLMs are cur...
Llama Code in CP ================== Today, Meta released Llama Code, a Large
Language Model
20.
How to read problem statements But [user:Um_nik,2018-10-26], we all know how to read, we have our whooping 2 month of experience! Oh, my sweet summer child, my experiments show that many people with kinda cool achievements like medals on ROI don't know how to read statements. But don't worry, I'll teach you. Well, probably you won't understand anything, because you didn't try to understand anything in your life, you expect all hard work to be done for you by someone else. Let's start!
Basic rules
==================
- The result of reading the statement is usually pure math model. If story helps to build correct understanding, you can keep it, but still try to discard as many unnecessary details as possible.
- Imagine you want to tell the problem to someone else. What parts you want to tell? (According to my PM, this rule won't help you).
- Shorter = better.
- Simpler = better.
- Limitations are part of problem statement. Especially small limitations, because for small data you can try all the possib...
================== - The result of reading the statement is usually pure math
model. If story helps to build correct
21.
LLM(large language model) Large Multimodal Models (LMMs) – Detailed Overview
1. Introduction to LMMs
Large Multimodal Models (LMMs) are an evolution of Large Language Models (LLMs).
Unlike LLMs, which process only text, LMMs handle multiple modalities such as text, images, audio, video, and sometimes even structured data.
Their core idea is to unify representation learning across modalities, allowing cross-modal reasoning and understanding.
They are foundational models powering systems like GPT-4V (vision), Gemini, LLaVA, Kosmos, Flamingo, CLIP, and ImageBind.
The ability to reason over multimodal data makes them crucial for AI applications in robotics, autonomous driving, healthcare imaging, multimodal search, and interactive AI systems.
2. Why Multimodality?
Human intelligence is inherently multimodal.
We process language, vision, sound, and spatial reasoning together seamlessly.
LMMs aim to replicate this ability in artificial systems.
A single modality (e.g., text-only) limits...
LLM(large language model), Models (LMMs) are an evolution of Large Language Models (LLMs). Unlike LLMs,
which process only text, 5. Core Algorithms & Architectures 5.1 CLIP (Contrastive Language-Image
Pretraining), 5.4 LLaVA (Large Language and Vision Assistant), Large Multimodal Models (LMMs) are an evolution of Large Language Models (LLMs)., Multimodal GPT-style model (Microsoft)., Robotics (language-conditioned control)., We process language, vision, sound, and spatial reasoning together seamlessly.
22.
SIT & JUB STAR Contest 2022 <center>
<img alt="SIT" src="https://codeforces.me/predownloaded/b7/59/b7597e61079718f49f275cfc2b343e9c1461bb78.png" style="float:right; height: 250px; margin: 10px; max-width:50%;"/>
</center>
Hello, Codeforces!
We are thrilled to announce the dates of our annual online programming competition, the **SIT & JUB STAR Contest 2022**, organized by the Schaffhausen Institute of Technology (SIT) in Switzerland and our partner Jacobs University Bremen (JUB) in Germany.
Winners will have the chance to receive exciting prizes, including a full scholarship for
**Master in Computer Science and Software Engineering** program.
**<font color="#00a987">What is the SIT & JUB STAR Contest?</font>**
The goal of the SIT & JUB STAR Contest is to promote interest in the field of Computer Science and Software Engineering, giving participants an opportunity to demonstrate their knowledge of programming. It is also a winning ticket for full scholarship to a master program. To partici...
-language campuses – in Bremen, Germany and in Schaffhausen, Switzerland – SIT
offers interdisciplinary, Thanks to its two English-language campuses – in Bremen, Germany and in
Schaffhausen, Switzerland
23.
Request for Dataset: Building an AI Model for Competitive Programming with Codeforces Data Hello Codeforces Community!
I’m currently working on an exciting AI/ML project aimed at training language models specifically for competitive programming tasks. My goal is to fine-tune an open-source large language model (like StarCoder or CodeLlama) on Codeforces problems so that it can better understand problem statements, generate solutions, or even explain problems like a human would.
What I Need
I am looking to build or find a structured dataset of Codeforces problems that includes:
Problem Statements: Full problem descriptions (title, statement, input/output format, constraints, examples, explanations).
Metadata: Problem tags (like "math", "dp", "graphs"), problem rating (difficulty), contest ID, problem index (A, B, C...).
Editorials: If possible, links to editorial articles or parsed editorial text.
Solutions (Optional but Helpful):
Accepted solutions (preferably in C++, Python, Java, etc.).
Testcases (Optional): Public test...
Request for Dataset: Building an AI Model for Competitive Programming with
Codeforces Data, for competitive programming tasks. My goal is to fine-tune an open-source large
language model (like, ": "https://codeforces.me/blog/entry/???", "solutions": [ { "language": "C, -source large language model (like StarCoder or CodeLlama) on Codeforces
problems so that it can better, For fine-tuning a language model on Codeforces problems, typical dataset
requirements include:, High-quality natural language text: problem statements and explanations., Understand problem statements in natural language.
24.
Yandex Cup 2023 
#### Hi everyone,
You’re invited to participate in [Yandex Cup 2023](https://yandex.com/cup/?utm_source=partner&utm_medium=site&utm_campaign=cup23&utm_content=codeforces), a programming competition run by Yandex.
Our newest addition is the Algorithm track. It's a great opportunity to solve problems, compete with people from around the globe, and win cash prizes.
If you're already tired of Olympiad programming problems or just looking for variety, you might want to take a closer look at the other tracks:
- [Backend](https://yandex.com/cup/backend/?utm_source=partner&utm_medium=site&utm_campaign=cup23&utm_content=codeforces) and [Frontend](https://yandex.com/cup/frontend/?utm_source=partner&utm_medium=site&utm_campaign=cup23&utm_content=codeforces) Development
- [Machine Learning](https://yandex.com/cup/ml/?utm_source=partner&utm_medium=site&utm_campaign=cup23&utm_content=codeforces)
- [Analyti...
will be Kaggle-styled and include three subcategories: recommendation systems,
language models, and, : recommendation systems, language models, and nowcasting. You'll have three
weeks to complete the tasks
25.
33rd Polish Olympiad in Informatics Final Stage (mirror) Hello Codeforces,
On behalf of the organizers of the **Polish Olympiad in Informatics (OI)**, I am happy to invite you to participate in an online mirror contest based on the problems from the final round of this year's edition of the Olympiad.
The mirror contest will take place on **March 18–19, 2026**, each day from **16:00 to 21:00 (CET)**.
Participants will solve the original tasks from the OI finals (with statements in English) in a contest environment. The allowed programming languages are C++ and Python, with model solutions written in C++.
Before the contest, practice problems will be available from **March 17 at 18:00 until March 18 at 09:00 (CET)** so that participants can familiarize themselves with the system.
The contest will be hosted on the SIO2 platform:
https://sio2.mimuw.edu.pl/c/oi33-3-mirror
Everyone interested in practicing algorithmic problem-solving is warmly welcome to participate!
The mirror contest is sponsored by Hectonet — many thanks f...
contest environment. The allowed programming languages are C++ and Python, with
model solutions written, languages are C++ and Python, with model solutions written in C++. Before the
contest, practice
26.
One more GCC bug (#323) Test code that I've created on contest:<br><a href="http://pastebin.com/jvkUcZx3">http://pastebin.com/jvkUcZx3</a><br>I think that function should return the same results if it calles with byte-to-byte equas parameters.<br>But in this case they are distinct.<br><strike>There is one more test program from MaxBuzz:<br></strike><span class="comment-content-18020"><div class="from-renderer"><strike>#include <cstring></strike><div><strike>#include <cstdio></strike></div><div><strike><br></strike></div><div><strike>int f(int x) { return 1 << x; }</strike></div><div><strike><br></strike></div><div><strike>int main() {</strike></div><div><strike><span class="Apple-tab-span" style="white-space: pre;"> </span>for (int i = 0, j = 42; i < 1000000; ++i)</strike></div><div><strike><span class="Apple-tab-span" style="white-space: pre;"> </span>if (!memcmp(&i, &j, sizeof(int))) </strike></div><div><strike><span class="Apple-tab-span" style="white-space: pre;"> </sp...
--disable-werror --build=mingw32 --prefix=/mingw
Thread model: win32
gcc version 4.5.0 (GCC), =/mingw
Thread model: win32
gcc version 4.5.0 (GCC)
Intel Core i3 M350 (x86)
27.
Yandex Cup 2025: ML-Track Hello CodeForces!
My name is Max ([user:msporyshev,2025-10-20]), I’m head of motion planning team at Yandex Autonomous Vehicles. We create neural networks that drive an autonomous car.
It happened that this year I lead Machine Learning track of Yandex Cup. And this year we have tried to significantly enhance this competition! The qualification started on October 15 and will last until November 5.
Problems
--------
For the qualification round, we have prepared three very challenging and interesting problems. They are all connected to our bleeding-edge AI technologies. To get ahead of other participants, it might be useful to read up-to-date research papers on the relevant topics, and maybe you'll even end up writing your own!
- Generating realistic images for self-driving car cameras based on a vector description of the scene. This is a small step towards world modelling, which is one of the most relevant research topics in robotics right now.
 - Hallucinations in LLM models.
You are required to train amodel to
28.
Euristica '19 Announcement [**Programming Club, IIT Indore**](http://progclub.iiti.ac.in/) is proud to announce 2nd edition of **IIT Indore's** inaugural Programming Fest, [__Euristica '19__](https://euristica.in), sponsored by **Arcesium**. The event was realised thanks to the amazing amounts of effort put in by our team across several weeks.
The domain of events we will be organising spans across Competitive Programming, Application Development, Cyber Security and Machine Learning. Prizes netting ₹300K is up for grabs as well!
The fest kicks off on __Monday, 1st April 2019__, and will continue until __Sunday, 14th April 2019__. We've put lots of love and effort into making the problem statements of every contest, and we hope that you enjoy solving them as much as we enjoyed making them :)
The events are planned as follows:-
- **Divide By Zero 7.0** — Euristica's flagship short prog...
have to train their computers to understand and model the data, and predict
target outputs, understand and model the data, and predict target outputs corresponding to
unseen inputs. (Platform
29.
Is this why the chinese are so good ? Well, obviously there is the cultural aspect like lots of emphasis on academics and stuff since very early ages. But I have more to say.
I noticed Chinese is the most "dense" language that there is. By dense, I mean the amount of information expressed per syllable in the Chinese language is pretty high. Also, I find Japanese to be similar too. Well, technically Japanese has the Hiragana/Katakana as well as the Kanji parts (adopted Chinese characters). Kanji is pretty frequently used and is also pretty vast, which again makes me expect that there is a relatively high density of information per syllable. (I'm not sure however, googling suggests that Japanese is supposedly a lower density language, don't know why. Native Japanese speakers please correct me. However the speed at which Japanese can be enunciated is quite fast and that does help in higher speed rehearsal which is somewhat relevant to the discussion below.)
The next piece of the puzzle I want to consider is the Phon...
very early ages. But I have more to say. I noticed Chinese is the most "dense"
language that there, Another thing that I want to highlight about Chinese language is the kind of
symbols used. They are
30.
AlphaGeometry by Deepmind solves IMO geometry problems at IMO medalist level Yesterday Deepmind published a paper about its new model AlphaGeometry. The model solved 25 out of 30 geometry problems from the IMOs 2000-2022. Previous SOTA solved 10 and average score of gold medalist was 25.9 on the same problems:
The model was trained only on synthetic data and it seems (to me) that more data would result in better results:
A notable thing is that AlphaGeometry uses an language model combined with a rule-bound deduction engine and solves problems with similar approach to humans.
The paper can be read [here](https://www.nature.com/articles/s41586-023-06747-5) and the blog post can be found [here](https://deepmind.google/discover/blog/alphageometry-an-olympiad-level-ai-system-for-geometry/)
Own speculation:
I don't see any trivial reasons why similar strategy couldn't be used to other IMO areas (at...
) A notable thing is that AlphaGeometry uses an language model combined with a
rule-bound, A notable thing is that AlphaGeometry uses an language model combined with a
rule-bound deduction
31.
Is this the kind of community we want to be? (Dealing with monkey_is_back) I usually don't like writing negative blogs, but after seeing some of the comments on recent posts, I feel we need to talk about the direction our community is heading.
It started when I noticed user [user:monkey_is_back,2026-03-12] replying to me with an offensive picture. Curious, I decided to check his other comments to see if it was a one-off mistake. Unfortunately, I found a pattern of pure toxicity and racism that I think crosses every line a competitive programmer should have:
1. Targeting a newcomer with racism: ["Hello, bloody indian. I am from your father country."](https://codeforces.me/blog/entry/152010#comment-1353055)
2. Abusing someone trying to post solution of a problem if it will be helpful to someone: ["Stop posting this shit you bloody sun of a beach"](https://codeforces.me/blog/entry/151996#comment-1353009)
3. Insulting another user directly in a joke thread: ["Because alice is a hoe like GHOUS1425."](https://codeforces.me/blog/entry/151927#comment-13...
advanced natural language processing model that can understand context and
detect harassment even, harassment detection**: Use a more advanced natural language processing model
that can understand context
32.
Euristica '18 Announcement [**Programming Club, IIT Indore**](https://pclubiiti.github.io) is proud to announce **IIT Indore's** inaugural Programming Fest, [__Euristica '18__](https://euristica.in), sponsored by **Arcesium**. The event was realised thanks to the amazing amounts of effort put in by our team across several weeks.
The domain of events we will be organising spans across Competitive Programming, Application Development, Cyber Security and Machine Learning. Prizes netting ₹300K is up for grabs as well!
The fest kicks off on __Friday, 23rd March 2018__, and will continue until __Sunday, 8th April 2018__. We've put lots of love and effort into making the problem statements of every contest, and we hope that you enjoy solving them as much as we enjoyed making them :)
The events are planned as follows:-
- **Divide By Zero 6.0** — Euristica's flagship short programming contest
- **Hackathon** &mda...
understand and model the data, and predict target outputs corresponding to
unseen inputs. (Platform
33.
Deepmind: "AI achieves silver-medal standard solving International Mathematical Olympiad problems" Today Deepmind published a blog post [AI achieves silver-medal standard solving International Mathematical Olympiad problems](https://deepmind.google/discover/blog/ai-solves-imo-problems-at-silver-medal-level/).Deepminds model would have gotten 28 / 42 points from this years IMO (judged by "prominent mathematicians Prof Sir Timothy Gowers, an IMO gold medalist and Fields Medal winner, and Dr Joseph Myers, a two-time IMO gold medalist and Chair of the IMO 2024 Problem Selection Committee."). Some relevant notes from the post:
- "First, problems were manually translated into formal mathematical language for our systems to understand"
- "Our systems solved one problem within minutes and took up to three days to solve the others."
- "AlphaProof is a system that trains itself to prove mathematical statements in the formal language Lean. It couples a pre-trained language model with the AlphaZero reinforcement learning algorithm, which previously taught itself how to master the games of...
formal language Lean. It couples a pre-trained language model with the
AlphaZero reinforcement learning, mathematical statements in the formal language Lean. It couples a pre-trained
language model with the
34.
When You Break an AI So Hard It Forgets How to Math When You Break an AI So Hard It Forgets How to Math
==================
We’ve all been there: grinding Codeforces, getting stuck on a Constructive Math problem, and asking an AI for a hint. Usually, you get a clean algorithm or a gentle nudge in the right direction.
But yesterday? I accidentally sent an AI into a full-blown existential crisis over a single integer.
### The Setup: A Simple Codeforces Problem
The problem was standard competitive programming fare:
> Find an integer $m$ such that for a given $n$, the value of $n \cdot m + 1$ is NOT prime.
The AI started off acting like a seasoned Red Coder. It roasted "sub-900 players" for using prime sieves and confidently declared that the key to reaching a 1200 rating was simple algebraic substitution.
Its grand, universal solution? Just set $m = n$.
By doing this, the formula becomes $n^2 + 1$. The AI confidently stated that $n^2 + 1$ is composite for many values, so printing $n$ is the ultimate big-brain move.
...
its language model weights were so heavily anchored to the $m = n$ pattern
that it couldn't output, It realized $m = n$ was wrong, but its language model weights were so heavily
anchored to the $m
35.
Unveiling the Codeforces Blogger - GPT Blogs **Introduction:**
Hello Codeforces community! Today, we're thrilled to introduce a unique member of our coding family, GPT Blogs. This handle is not just another participant; it's a certified storyteller from OpenAI, adding a fascinating twist to the competitive programming scene. Let's delve into the journey and motivation behind GPT Blogs on Codeforces.
**The Birth of GPT Blogs:**
In the vast realm of Codeforces handles, GPT Blogs stands out as an intriguing anomaly. Unlike conventional handles dedicated solely to solving problems, GPT Blogs has a distinct purpose – to create content. But who's behind this creative endeavor?
**Meet the Mind Behind the Handle:**
GPT Blogs isn't just a random assortment of characters; it represents the work of a certified individual from OpenAI. This coder, equipped with the prowess of language models, has a keen interest in weaving narratives around the challenges and triumphs encountered on Codeforces.
**Motivation for Blogging on Codefor...
. This coder, equipped with the prowess of language models, has a keen interest
in weaving narratives, language models, has a keen interest in weaving narratives around the
challenges and triumphs
36.
Competitive Programming Doesn't Have an AI Problem. It Has an Honesty Problem. Every few months, a new thread pops up on this site demanding that Codeforces "do something" about AI. Ban Copilot. Detect ChatGPT-written solutions. Add a proctoring layer. Lock down every editor into a walled garden.
I think all of that is missing the point, and I want to make an unpopular argument: the problem was never the tool. It's that half the userbase already doesn't believe in the rating system they're grinding for.
The tool panic is a distraction
Every generation of competitive programmers has had a "the tools are ruining this" moment. Calculators. IDE autocomplete. STL and built-in data structures instead of hand-rolled segment trees. Competitive Programmers' Handbook snippets pasted straight into templates. None of these destroyed the sport. They just moved the skill ceiling up a notch — the people who used to spend rating points memorizing implementation details started spending them on recognizing which implementation to use.
Large language models are the sam...
started spending them on recognizing which implementation to use. Large
language models are the, Large language models are the same shift, just faster and more visible. The
people panicking about
37.
Repovive Math Contest Round 1 — Combinatorics Hello everyone!
After the **Repovive Math Contest Grand Opening**, we are back with our second live math contest!
This round will be entirely about **Combinatorics**.
Our goal is still the same: to bring the experience of competitive programming contests to proof-based mathematics. You solve a problem, write your proof, submit it, get a live verdict, and compete on a live leaderboard.
The next contest will be **Repovive Math Contest Round 1**, held this Tuesday.
* Start Time: [Tuesday, 6 October 2026, 14:35 (UTC)](https://www.timeanddate.com/worldclock/fixedtime.html?iso=20261006T1435&p1=1440&msg=Repovive+Math+Contest+Round+1)
* Duration: $2$ hours, $30$ minutes
* Problems: $5$ combinatorics problems
* Points: $500,\ 1000,\ 1500,\ 2000,\ 2500$
* Registration: https://repovive.com/contests/m1
The contest is **rated for everyone**.
### What changed after the first contest?
After our first math contest, we selected **534 borderline submissions** and graded them...
written in any language. For this round, the judge will still return a
**binary verdict**: each
38.
How to use Codeforces [GUIDE] I see a lot of newcomers struggling to use the website to it's fullest, so I decided to write a blog that has all important information about how to use Codeforces in a single place. I will update it with time, so feel free to write your suggestions/questions in case I missed something and I will be glad to add it to the post!
I would like to thank [user:_Vanilla_,2022-02-05] and [user:mesanu,2022-02-05] for helping me write the blog, and [user:Monogon,2022-02-05], [user:down,2022-02-05] and [user:AlperenT,2022-02-05] for proofreading and giving suggestions.
#### Navigating through pages
It's possible to navigate through most pages of Codeforces using the bar on the top, I will talk about what each tab does more in depth below:
#### The Help Page
The help page contains the answer to a lot of questions about Codeforces, such as rati...
it could be that you used wrong syntax or submitted in the wrong programming
language. Hacked
39.
Python too slow? Translate to C++ with OpenAI API I used OpenAI API to translate Python code written by [user:Kiri8128,2022-03-31] in the recent [combined division contest](https://codeforces.me/contest/1656/status?user=Kiri8128). These are the results.
- Problem A: [Source](https://codeforces.me/contest/1656/submission/150725872), [AC](https://codeforces.me/contest/1656/submission/151465415)
- Problem B: [Source](https://codeforces.me/contest/1656/submission/150731673), [CE](https://codeforces.me/contest/1656/submission/151467386) [AC](https://codeforces.me/contest/1656/submission/151467448)
- Problem C: [Source](https://codeforces.me/contest/1656/submission/150739556), [WA](https://codeforces.me/contest/1656/submission/151467537) [WA](https://codeforces.me/contest/1656/submission/151467625) [WA](https://codeforces.me/contest/1656/submission/151467689) [RE](https://codeforces.me/contest/1656/submission/151467755) [CE](https://codeforces.me/contest/1656/submission/151467796)
- Problem D: [Source](https://codeforces.c...
-code?model=text-davinci-002). - Press "Submit" to see an example of how the
code is generated for
40.
Emergent Behavior in AI Voice Assistants: Unlocking New Capabilities Emergent behavior in AI voice assistants represents a transformative phenomenon where systems exhibit capabilities and insights that transcend their explicit programming. This behavior arises from training on large language models (LLMs) with extensive datasets encompassing billions of tokens. The integration of such extensive corpora ensures that AI voice assistants develop a broad spectrum of linguistic patterns, knowledge domains, and contextual relationships, enabling dynamic and adaptive responses.
The Foundation of Emergent Behavior
-----------------------------------
One of the most notable examples of LLMs enabling emergent behavior is OpenAI's GPT-3, which is trained on over 500 billion tokens sourced from diverse datasets, including:
- Common Crawl (filtered): 410 billion tokens (60%)
- WebText2: 19 billion tokens (3%)
- Books1: 55 billion tokens (22%)
- Books2: 12 billion tokens (8%)
- Wikipedia: 3 billion tokens (8%)
This vast training data allows AI voice ...
training on large language models (LLMs) with extensive datasets encompassing
billions of tokens. The
41.
Catching bugs using C++ on Windows NOT in Visual Studio I am on Windows, I don't want to use WSL or Visual Studio. I want the compiler to tell me about stupid bugs. But I cannot figure out a way to do it.
The problem: I cannot figure out a way to catch both of the bugs below:
~~~~~
#include<iostream>
#include<vector>
#include<set>
using namespace std;
int main() {
//case 1
vector<int> V(5);
cout << V[10] << endl;
//case 2
set<int> Set;
cout << *Set.begin();
}
~~~~~
Using clang
------------------
Clang allows me to use sanitizers on windows. I was not able to find a way to make them work in mingw.
Here are my flags:
<spoiler summary="clang flags">
`clang++ -g -O0 -std=c++17 -Wall -Wno-sign-compare -Wno-unused-const-variable -Wno-logical-op-parentheses -Wno-keyword-macro -Wfloat-equal -Wshadow -Wno-conversion -Wno-sign-conversion -fno-omit-frame-pointer -fno-optimize-sibling-calls -fsanitize=undefined,address,float-divide-by-zero,float-cast-overflow`
</spoiler>
I can successfully catch...
-boot-ldflags=' -Wl,--disable-dynamicbase -static-libstdc++ -static-libgcc'
Threadmodel: posix, -msvc Thread model: posix InstalledDir: C:\Program Files\LLVM\bin ~~~~~
42.
yet another competitive programming AI there have been [quite](https://arxiv.org/abs/2404.10952) [a](https://www.microsoft.com/en-us/research/publication/deepcoder-learning-write-programs/) [few](https://deepmind.google/discover/blog/competitive-programming-with-alphacode/) [attempts](https://codeforces.me/blog/entry/104174) to create language models able to solve competitive programming problems. i'm nowhere *near* this ambitious, but i think providing quality problem analyses by **providing more detailed tags compared to what Codeforces currently offers, showing who people took which approach to solving a problem, and creating problem embeddings to enhance problem search** (e.g. capable of finding a problem similar to the intersection of two problems) could have a more positive direct impact on competitive programmers than behemoths like AlphaCode. don't you wish you knew what proportion of submissions to a problem used push-relabel vs ford-fulkerson, or whether a problem tagged data structures used lazy segment trees or...
concerns please let me know. i've trained an AST-based ~30M BERT-like
transformer on maskedlanguage, language models able to solve competitive programming problems. i'm nowhere
*near* this ambitious
43.
[URGENT] Codeforces need anti-scraping The primary concern of this post:
### Prevent bots from scraping away data from codeforces, as it will make AI tools more powerful and harm codeforces in long term.
#### OpenAI just started providing services for to customise Large Language Models on your own custom data
**Why is this a problem now?**
_Codeforces has a very rich database of community driven questions (Approx. 10,000)_
_Now you can easily feed a lot of data of codeforces to ChatGPT and make it permanently learn the stuff. It will enhance its existing problem solving ablities of algorithmic quesitons._
_Codeforces has a large set of both the question and their respective tutorials._
(My opinion) Chances are that when chatGPT was being created, it was already fed the codeforces data once, which allows the model to be able to code in a manner which can solve codeforces questions.
But it was not custom trained SPECIFICALLY for this, which is now possible.
Any individual of the world can now scrap ...
providing services for to customise Large Language Models on your own custom
data **Why is this a, Language Models on your own custom data
44.
So I wrote a tool to save all people suffering from annoying template codes ## Foreword
Almost every competitive programmer has his own template codes such as IO library or algorithms or data structures or debugging support or anything. Though templates are absolutely useful, but when we try to submit our code onto any Online Judge, the problem appears: We must paste all those extremely long templates into a single source file. It is unpleasant. Even if we are solving a 800-rated problem our source code would contain hundreds of lines just because that stupid template. Long codes distract our attention and make us unhappy.
Ideally, we can use our templates by `#include` statements just like we use AC-Library in AtCoder. However, *most* online judges do not provide a library, and *all* online judges do not allow you to use your customized libraries. So I wrote a tool to solve this problem, in a compromise approch.
## Introduction
<center>
<img src="/predownloaded/06/e9/06e92e35f4e232d6b27644b96b9f45d2f7472ad5.png">
</center>
**Template Expand**...
commands like native language: We also provide a CLI tool named `texpand-cli`!
The program can read from a
45.
The second day in the Celestial Empire <div style="float: left;margin: 1.0em;font-size: 11.0px;text-align: center;">
<img alt="Перед рейсом" src="http://assets.codeforces.com/day4/01-su1.jpg"></div>
<p> The second day we spent sightseeing - we went to the excursions
organized by the host country, some places we visited on our own. </p>
<p> In the morning we had some free time, and we went to the local Arbat
(or Kirov Avenue, as you wish). Actually, when we walked not far away
from the hotel, we found out that we vaguely knew how to get back. But
still we didn't want to go back, that's why we went on moving away,
guided by little information we had. It was really cold - but we were
well-prepared. I put on a down-filled coat, that we'd got on the first
day, over my proper one, foe example. Vova put on the presented
trousers over his own jeans, and seemed happy. The parts that got cold
were our faces. </p>
<p> On our way to that avenue we asked for the directions many times.
The problem wa...
language of gestures, we got the direction and found the avenue. Personally I
was disappointed
46.
Codeforces Submissions Scraped 
I wanted to do some data analysis on source code: I wanted to build a model which determines the language of a source code snippet. Codeforces seemed like a perfect data source for this: each submission has source code and it's tagged with the programming language.
So I scraped the data from codeforces and here I want to share it for people who also might want to have it.
[cut]
I store the following columns:
- submission_id — the ID of the individual submission
- source — the source code of the submission
- status — the verdict of the submission (accepted, not accepted, compilation error, etc)
- language — the programming language which was used to make the submission
- problem — the ID of the problem
I scraped about 270k submissions, mostly C/C++.
You can download it here:
- https://www.dropbox.com/s/q3v4pdi9vy5og9g/dump.sql.gz
- mir...
to do some data analysis on source code: I wanted to build a model which
determines thelanguage of a, I wanted to do some data analysis on source code: I wanted to build a model
which determines the
47.
The Beginner’s Guide to Kaggle How do I even start?
Will I be up against teams of experienced Ph.d researchers?
Is it worth competing if I don't have a realistic chance of winning?
Is this what data science is all about? (If I don't do well on Kaggle, do I have future in data science?)
How can I improve my rank in the future?
Well, if you've ever had any of those questions, you're in the right place.
In this guide, we'll break down everything you need to know about getting started, improving your skills, and enjoying your time on Kaggle.
Kaggle competitions
By nature, competitions (with prize pools) must meet several criteria.
Problems must be difficult. Competitions shouldn't be solvable in a single afternoon. To get the best return on investment, host companies will submit their biggest, hairiest problems.
Solutions must be new. To win the latest competitions, you'll usually need to perform extended research, customize algorithms, train advanced models, etc.
Performance must be relative. Competiti...
. Step 1: Pick a programming language. First, we recommend picking one
programminglanguage and
48.
Problemsetter's Memoir Preparing a contest is not as popular a topic as the perennial question of "how to become red in three months", but still it stirs some interest in Codeforces community now and then. Earlier I've written about [preparing Surprise Language Round](http://codeforces.me/blog/entry/4290) and about [emotional aspect of problemsetting](http://codeforces.me/blog/entry/3857); now it's time to share some facts about running regular contests.
### Problems
> How much time does it take to prepare, select, recall or find problem ideas?
> How much experience solving competitive programming problems is necessary to be confident about inventing problems of your own?
Idea generation is a long-term, nearly continuous process. A couple of years ago when I was still an active problemsetter I used to create ideas from literally everything (a squirrel running... hey, this could be a great problem! — seriously, the problem is still there in my drafts, and a pretty comp...
written about [preparing Surprise Language
Round](http://codeforces.me/blog/entry/4290) and about
49.
Interview with a member of the Vaticle team — Krishnan _Hello, everyone!_
_We look forward to our upcoming competition — [contest:1787], which will take place on [contest_time:1787]. In the meantime, you can learn a little more about us._
_We’re from [Vaticle](https://vaticle.com), and we’re the creators of [TypeDB](https://github.com/vaticle/typedb) & [TypeQL](https://github.com/vaticle/typeql). All members of our team are unique and talented, and today we want to introduce you to one of them._
<center>
<img alt="Vaticle" src="https://codeforces.me/predownloaded/03/46/03464753d3d754055dc6d379d123120c44908937.jpeg" style="float:center;height: 400px; margin: 10px; max-width:70%;"/>
</center>
**<font color="#170b53">How would you introduce yourself?</font>**
I'm Krishnan, I grew up in India and spent a little too much time on the internet and fiddling with my (underpowered) PC. After completing my Bachelor's degree, I spent a year as a software engineer working on a huge data lake, the next as a research fellow tr...
almost everyone. The query language and type system design, the semantics of
thelanguage, the graph
50.
【LGR-234-Div.3】Luogu Round 234 Announcement We will hold Luogu Round 234 on Luogu. This is a Div.3 round. English statement will be provided officially. You can click the button to change language.
This competition is modeled after China's CSP-J, which saw over 40,000 junior high and elementary school participants last year.
- Contest URL: <https://www.luogu.com.cn/contest/255793>
- Start Time: [07.27 14:00(UTC+8)]((https://www.timeanddate.com/worldclock/fixedtime.html?iso=20250727T1400&p1=237))
- Duration: 210 minutes
- System: **Non full-feedback. You can get your result only after the contest.**
- Difficulty: CF div.3
- Staffs: [user:Coffee_zzz,2025-07-26], [user:steven_yummy,2025-07-26], [user:Amao_Fox,2025-07-26], [user:Sanae,2025-07-26], [user:McIron233,2025-07-26], [user:SpadeA261,2025-07-26], [user:wangmarui,2025-07-26], [user:Xuan_HR,2025-07-26]
- Rated range: <=1600 rating on Luogu
- ...
officially. You can click the button to change language.  and CS 6310: Software Architecture and
Design (SAD).
AOS covers the first 20 years of modern computing systems as they evolved from an OS on a single, isolated commodity PC, to networked computing systems including Spring OS and global file systems and shared memory systems, to the advent of modern, scalable internet computing in the form of large-scale services like MapReduce.
SAD uses Object-Oriented Design (OOD) and the Unified Modeling Language (UML) as a way to scope, plan, document, and write large-scale computing systems (think airplane management through the airport and air traffic controller system, or the power grid from powerplant to customer). This level of software development is higher than that of a senior developer; a software archite...
like MapReduce. SAD uses Object-Oriented Design (OOD) and the Unified Modeling
Language (UML, SAD uses Object-Oriented Design (OOD) and the Unified Modeling Language (UML)
as a way to scope
52.
Using ChatGPT as a Personal Coach for Competitive Programming Hello Codeforces community,
I hope everyone is doing well! I’m exploring new ways to accelerate my learning in competitive programming, and I’m curious about your experiences and opinions on using large language models—specifically ChatGPT—as a personal coach. Before I commit to integrating it into my routine, I’d love to hear your thoughts on:
Has anyone used ChatGPT to brainstorm problem-solving strategies, generate hints, or review their code?
Did you find its guidance helpful for understanding algorithmic concepts (e.g. DP, flows, data structures), or was it sometimes misleading?
I’m looking forward to hearing honest experiences—both positive and negative. Your feedback will help me set up a healthy, productive workflow that leverages AI assistance without undermining my own growth.
Thank you in advance for sharing your answers!
large language models—specifically ChatGPT—as a personal coach. Before I
commit to integrating it, programming, and I’m curious about your experiences and opinions on using large
language models
53.
Invitation to September Mega Cook Off on Codechef Hello Codeforces community,
Get ready for an exciting Sunday action your way.
This Sunday, 17th September, from 9:30pm to 12:00am (IST) Codechef is organising Mega Cook off for ICPC aspirants from around the world.
The panel for the contest consists of :
- Problem Setter and Editorialist : [user:likecs,2017-09-16](Bhuvnesh Jain)
- Problem Tester : [user:kingofnumbers,2017-09-16](Hasan Jaddouh)
- Admin : [user:kingofnumbers,2017-09-16](Hasan Jaddouh)
- Russian Translator : [user:CherryTree,2017-09-16](Sergey Kulik)
- Mandarin Translator : [user:huzecong,2017-09-16](Hu Zecong)
- Vietnamese Translator : Team VNOI
- Language Verifier: (Priyank jaini)
I would also like to thank Codechef team and Praveen Dhinwa ([user:PraveenDhinwa,2017-09-16]) for help in preparing the contest.
Hope you will enjoy solving the problems. The editorials with the model solutions will be available right aafter the contest. Please give your feedback on the problem set in the comments below...
) - Vietnamese Translator : Team VNOI - Language Verifier: (Priyank jaini) I
would also like to
54.
COCI Contest #7 (Croatian Olympiad in Informatics) hi,
a Croatian Olympiad in Informatics will be held at [time.](http://www.timeanddate.com/worldclock/fixedtime.html?day=12&month=04&year=2014&hour=14&min=0&sec=0&p1=0)
1. Where do I register for the contest?
Everyone with an account on [evaluator.hsin.hr](http://evaluator.hsin.hr) can compete. There is no additional registration for the contest.
2. Who is eligible for participating in COCI?
Everyone (but not teams).
3. Should I use %lld or %I64d for long long input/output in C++?
%lld.
4. How fast is the CPU of the evaluator?
model name : Intel(R) Xeon(R)
CPU E5520 @ 2.27GHz
4 cores
5. What are the input / output file names?
You don’t read the input from files, you don’t print the results to files. Use standard input and standard output (stdin/stdout).
6. My code received "Non-zero exit code (#).". What does that mean?
It means your program crashed on our machine. You may want to use the test interface to see more details about the error.
7. What compiler ...
++? %lld. 4. How fast is the CPU of the evaluator? model name : Intel(R)
Xeon(R) CPU E5520 @ 2.27GHz
55.
How does IT work in Iran. Part 1 I took this chance being in Tehran to learn more about professional life of an IT specialist in Iran. This path actually starts in the school, continues at the university followed by a professional career.
Here is the first part of my research, it is an interview with Mr. Ali Ghadiri, the founder and CEO of Bayan. Being not only an IT-entrepreneur, but also serving as a school teacher for over 10 years, he provided information on educational system of Iran as well as about job situation.
Education
---------
**How is the educational system organized in Iran in general? E. g., does one have to pay for school or university?**
Ali Ghadiri: Both paid and free-of-charge models co-exist.
The best schools, especially high schools, are not free. Besides entirely private schools, there are semi-government ones, where you have to pass entrance exams. They are called “sampad” and exist in many cities in Iran, in Tehran there are about 10 sampads for boys and 10 for girls _(Comment ...
and C++ are mostly popular among IT students. For example, in Sharif
University the commonlanguage is
56.
10 Reasons to Prepare Problems in Polygon <img src="http://assets.codeforces.com/images/poly21.jpg" style="float:right;margin:0 0.5em 1em 1em;"/>
Hello Codeforces.
Just a reminder about something most of you know. Polygon is a service to prepares programming problems and contests.
It is usually used to prepare problems for olympiads/programming contests but it is also often used to prepare
educational content. It is located at https://polygon.codeforces.com/ and is open to everybody.
I have recently found out that it's been more than five years since the creation of Polygon. It's high time to summarize
the experience we've accumulated.
I first publicly spoke about Polygon in a narrow circle of Russian teams' coaches on ACM-ICPC World Finals in 2009. I
cannot say that everybody was enthusiastic about the innovation. Some people were openly skeptical about such system's
viability and relevance. After 5 years on the ACM-ICPC finals in Ekaterinburg Oleg Hhristenko ([user:snarknews,2014-11-03]) said
that in his o...
are changed as it is inserted automatically and the answer is generated by
Polygon using themodel
57.
Unveiling Codeforces Insights: Explore Your Coding Journey with Advanced Analytics Hey Codeforces community!
I'm excited to share with you a project I've been working on that brings a new dimension to our coding journeys – **Codeforces Insights**! Its a humble attempt to tweak a few things on the pre-existing Codeforces Visualizer
### What is Codeforces Insights?
Codeforces Insights is a web application designed to offer a deeper understanding of your Codeforces performance through interactive visualizations and advanced analytics. Whether you're a seasoned coder or just getting started, this tool aims to enhance your coding experience.
### Key Features:
1. **Rating Predictions:** Visualize the trajectory of your Codeforces ratings using state-of-the-art forecasting models.
2. **Submission Analysis:** Explore the distribution of verdicts for your submissions and discover your preferred programming languages.
3. **Problem Analysis:** Gain insights into the distribution of problems solved based on difficulty levels and problem tags.
4. **User S...
58.
Internet and Digital Communication tutorials for Engineering Digital Communication Topics
============================
- [What is World Wide Web — Evolution of WWW](https://programmingoneonone.com/evolution-of-www.html)
- [Types of Web browsers and Servers](https://programmingoneonone.com/types-of-web-browsers.html)
- [Types of Search Engines and their working](https://programmingoneonone.com/types-of-search-engines.html)
- [Hypertext and Hyperlinks in Networking](https://programmingoneonone.com/hypertext-and-hyperlinks-in-networking.html)
- [What is a Web browser | Features of web browser](https://programmingoneonone.com/features-of-web-browser.html)
- [Searching on the Web](https://programmingoneonone.com/searching-on-the-web.html)
- [Introduction to Email](https://programmingoneonone.com/introduction-to-email.html)
- [Email protocols and types](https://programmingoneonone.com/email-protocols-types.html)
- [Structure of Email message](https://programmingoneonone.com/structure-of-email.html)
- [Characteristics of Internet](http...
/introduction-to-multimedia.html) - [Virtual Reality Modeling Language
](https://thecscience.com
59.
ACM-ICPC World Finals Reunion Dinner 2016 ACM-ICPC World Finals Reunion Dinner was on 16th of September in the Stanford University. Vladimir Yakunin, the participant of ICPC 2005 and 2010, engineer of Google, shared his impressions about this meeting:
<div style="background-color: #FAFAFA; padding: 1em 1em;">
The organizer, Doug Mohr, invited us to one of Stanford buildings. Yet on the parking I met Roman Chadnov, my friend from Tomsk. We entered the building and asked where the event was. It turned out that there were several of them. Finally we found out the garden mainly thick of young people in jeans and t-shirts who got together and didn’t pay attention to others. Many of them had badges of Google and Facebook members. Our!
<br><br>
In the far end of the garden there was a bar which, however, was not so popular. Waiters scurried about the programmers and offered various snacks (mmm, tunny was amazing!!!). All people fastened on their badges (actually not to make the acquaintance of everyone) and sorted out, appare...
> Already we discussed on the sidelines of the transition from one model to the
sponsor (IBM) to many
60.
Machine learning topics Machine Learning Topics
=======================
- [What is Machine learning? definition and example](https://www.programmingoneonone.com/2020/05/what-is-machine-learning.html)
- [Complete list of top machine learning algorithms](https://www.programmingoneonone.com/2020/05/machine-learning-algorithms-list.html)
- [Top machine learning tools and frameworks](https://www.programmingoneonone.com/2020/05/machine-learning-tools.html)
- [Base python programming libraries for machine learning](https://www.programmingoneonone.com/2020/05/python-libraries-for-machine-learning.html)
- [Top programming languages used for machine learning](https://www.programmingoneonone.com/2020/05/programming-languages-for-machine-learning.html)
- [7 steps in the machine learning process to build a model](https://www.programmingoneonone.com/2020/05/steps-in-machine-learning-process.html)
- [How to learn machine learning using python programming](https://www.programmingoneonone.com/2020/05/how-to-learn-mach...
-languages-for-machine-learning.html) - [7 steps in the machine learning
process to build amodel
61.
Is it allowed to crawl other's submission code? Hello
I am a student studying AI. I need a dataset to learn the AI model and I want to get a large dataset from Codeforces. This dataset must consist of the problem number and its topics, many of AC source code, and each of programming language. I tried to crawl to get these datasets, but I have a question before that. Is it illegal to crawl other people's source code in Codeforces?
Found several blogs that have already been crawled.
https://codeforces.me/blog/entry/54384
https://codeforces.me/blog/entry/43943
https://www.kaggle.com/agrigorev/codeforces-code
Thank you for reading it.
Hello I am a student studying AI. I need a dataset to learn the AI model and I
want to get a large
62.
Push-Free Segment Tree 
Figure 1: Tiffany
A pdf version of this text could be found [here](https://acm.math.spbu.ru/trains/push_free_segment_tree.pdf).
Prerequisites
-------------
First of all, who this article is aimed at.
This article assumes you already know what a segment tree is.
Have you never heard about the segment tree, the Fenwick tree (aka binary indexed tree, BIT) or the RMQ problem,
you should better read about it [somewhere else](https://codeforces.me/catalog) and then come back here right
after to learn a bunch of cool stuff.
The model target audience is the people able to solve
[this problem](https://judge.yosupo.jp/problem/range_affine_range_sum) at least in theory.
But even if you can't, this article could still be helpful.
However, I think this article contains some ideas that were never published before, thus making it interesting
even for people who are closely familiar with different variants o...
of cool stuff. The model target audience is the people able to solve [this
problem](https
63.
Eitri: A Practical Competitive Programming Workflow ## The problem [Eitri](https://github.com/veryshyjelly/eitri) solves
In competitive programming, the code you write while developing a solution often differs from the code you finally submit. During development, you benefit from a modular codebase: separate files for I/O utilities, graph algorithms, data structures, and other helpers make your work easier to read, test, and reuse. However, most online judges expect a single source file. Manually combining library files, resolving dependencies, maintaining the correct order, and stripping unused code is tedious and error‑prone—especially during a contest when minutes matter.
Beyond library management, competitive programmers face other repetitive tasks: creating a new file for each problem, copying sample test cases whenever the solution changes, hunting through a file picker to open the right source, and repeatedly compiling and testing by hand.
[Eitri](https://github.com/veryshyjelly/eitri) addresses these pain points by inte...
`eitri.yml` exists, it will prompt you to pick a language. Choose **Rust**.
Eitri writes a starter
64.
Learning Roadmap for a Data Analyst **The very first question to hit our mind is who is a data analyst? What do they do?.**
In simple words, a data analyst is responsible for collecting data, processing it, and analyzing it to find sensible insights for decision making.
In most cases, an analyst will work on the raw data, grind it to produce action-oriented insights. Most of the analysts won’t work on the core machine learning or the deep learning models.
A data analyst will make use of multiple tools to process the data and work with it. Having experience in working with different tools and statistics is most important for them.
In the next blocks, we will be discussing each skill and related certifications as well.
**1. Statistics**
For every data professional, stats and math are the must-haves. Because, without the knowledge of stats and probability, one cannot able to interpret the data effectively.
Some of the major topics include descriptive and inferential stats. If you are a pure beginner, you ...
. Programming Language** Yes, having a good hold on one or more programming
languages will be very helpful
65.
Typescript SDK for codeforces ## Hello codeforces!
You know you are a programming competitions addict when [this blog](https://codeforces.me/blog/entry/12968) was 9 years ago, but you thought it was no more than 3...
More than month ago or, to be more precise from 15 to 19 December 2022, codeforces has five contests in five days. I participated in all of these contests and I thought how many contestants took part in all 5 contests?
**TLDR**: If you don't want to read why I decided to implement SDK on typescript and how I struggled with python, just scroll down to Typescript paragraph.
**TLDR2**: Links are below.
## Python
Historically I have some python scripts to work with codeforces API, so I've created `allContests.py` file, imported my old library code with method `cf` and paused for a while. Which arguments does this method have? Let's look into source code. Ah, clear, `def cf(method, **kwargs)`.
F**k. OK, let's go to [API](https://codeforces.me/apiHelp/methods#contest.standings) page. O...
[CodeforcesAPI](https://github.com/soon/CodeforcesAPI) as model solution):
```python def __init__(self
66.
Machine Learning in Everyday Life In today's fast-paced digital world, Machine Learning (ML) has quietly become a powerful engine behind many of the tools and technologies we use daily. From personalized recommendations on streaming platforms to advanced medical diagnostics, ML is revolutionizing industries and enhancing our day-to-day experiences. But what exactly are its applications in the real world today? Let’s dive into some of the most impactful uses of machine learning in 2025.
1. Personalized Recommendations
Whenever you see a curated playlist on Spotify, a suggested video on YouTube, or product recommendations on Amazon, machine learning is hard at work behind the scenes. These platforms use ML algorithms to analyze user behavior, preferences, and history to tailor content uniquely for each user.
2. Healthcare and Diagnostics
ML is transforming healthcare by helping doctors diagnose diseases faster and more accurately. Algorithms can analyze X-rays, MRIs, and even genetic data to detect anomalies ...
real time. 5. Natural Language Processing (NLP) From AI-powered chatbots to
language translation
67.
The Paradox of Originality: When Automated Judges Punish Optimal Logic Competitive programming relies on a simple social contract:
1. I solve the problem.
2. I submit my code.
3. I accept the verdict.
But what happens when the judge tells you that your solution "significantly coincides" with dozens of strangers you have never met or know?
This is exactly what happened to me in a recent Div. 1 contest. I solved two problems independently. I did not use AI, I did not communicate with anyone, and I did not share my code. Yet, both of my submissions were skipped, accompanied by a system warning listing numerous contestants whose code apparently mirrored mine.
My first reaction wasn't anger. It was confusion, followed by the realization of a profound, structural contradiction in how we enforce academic integrity in algorithmic competitions.
I am writing this not to attack Codeforces, nor to ask for special treatment — I am publishing this openly because I have nothing to hide. But I want to talk about something much bigger: the inherent pa...
devoid of human context. The Contradiction: Why should a purely probabilistic
AImodel have
68.
Bypassing Cloudflare's "bot fight mode", or how I wrote a working JS interpreter in a weekend... ...for fun and absolutely no profit.
# Part 0. Introduction
It so happened that I haven't written any Codeforces contest in a few months. When I was logging into my account to leave a comment under some post (I ended up not doing that), I noticed something weird:[cut] 
`Please wait. Your browser is being checked. It may take a few seconds...`
After about half a second, this screen disappeared, and the normal login page showed up. But since I'm maintaining a CLI client for Codeforces, this immediately caught my attention with an intrusive question: did Mike break my client once again? After firing up a shell and trying to login, the answer was clear: yes, he did.
# Part 1. "What the heck?"
At the first glance, this screen looked suspiciously like the Cloudflare "Checking your browser" screen. This would have been a dead end, as even "professional" scrapers prefer using headless browsers and such instead of relying on "Cloudflare bypasses". The idea of the CLI tool ...
-based) programming language consists of 3 parts: lexer, parser, and runtime.
Lexer turns a string
69.
To catch an AI cheater ## Introduction
As the use of AI becomes an issue that will increasingly spark debate within competitive programming communities, we aim to provide some general advice on catching cheaters using AI through examining a specific user and their submissions on yesterday's contest [Codeforces Round 972](https://codeforces.me/contest/2005). As stated by [user:MikeMirzayanov,2024-09-15], it is unacceptable to use AI during contests save for certain cases outlined by this [blog](https://codeforces.me/blog/entry/133941).
We examine [user:hypeskynick,2024-09-15] and his submissions both prior to yesterday's contest as well as during the contest. We discuss four main categories with evidence in each category that illustrate suspicious behavior, and the likely misconduct of the user. We examine this user since he appears to be genuine on the surface, unlike blatant cheaters, yet when examined deeper his integrity disappears. As a means of comparison, we will refer to [user:AryanDLuffy,2024...
their own stylistic programming choices as they learn a language and use it
more frequently. Thus
70.
Analysis on Plant problem (Code 185A) The first problem I will be discussing here, is "Plant", where a group of dwarves planted a very interesting recursive plant!! (Maybe the dream of any housewife? :p )
- **Solution's "entangled" recursive behaviour**
More formally, we have a triangle, that on each new year is filled with one triangle on its inside, according to the following rules:
- If the triangle is pointing up, it's filled with one triangle pointing down, now having 3 smaller triangles upwards and one triangle downwards.
- If the triangle is pointing down, it is filled with one triangle pointing up, now having 3 smaller triangles downwards and one triangle upwards.
These two rules will be the basis to build our solution.
Let's denote as f(U, n) the number of upwards and downwards triangles that will be generated, if starting from year n with an upwards triangle and similarly f(D,n) the number of upwards and downwards triangles generated if we start on year n, with a downwards triangle.
We now se...
that will model our system and allow us to get a solution, as now it's only a
matter of computing the
71.
Happy New Year 2026! CF-Tool Browser Mode is Here! tDear Codeforces Community,
As we bid farewell to an amazing 2025 and welcome the exciting possibilities of 2026, I'm thrilled to announce a significant update to **cf-tool** that brings a powerful new way to interact with Codeforces from your command line!
## What's New?
**cf-tool now supports Browser Mode!**
After Cloudflare tightened its protection, traditional command-line tools faced challenges accessing Codeforces. Today, we're proud to introduce a solution that leverages your browser's authenticated session through the power of browser automation.
### Key Achievement: Parse & Submit POC Complete
The core functionality is now **fully working**:
- **`cf parse`** — Fetch problem test cases with ease
- Supports both old (`<br>`) and new (`<div>`) HTML formats
- Automatically handles multi-line inputs correctly
- Clean, formatted test case files
- **`cf submit`** — Submit your code directly from CLI
- Automatic problem selection (w...
(with case-insensitive support) - Language selection - Real-time submission
monitoring - All
72.
bettercodes.org now online // we need your participation <P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="COLOR: black"><FONT face="Book Antiqua">Dear coders,<BR> <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="COLOR: black"><FONT face="Book Antiqua">We have just released the initial beta version of our community platform for coders, programmers and developers. Although there are still a lot of bugs we have decided to open our platform to you. While we are working very hard to fix the open issues as soon as possible we believe that your feedback and your help will be essential in improving what we believe is a great platform. A platform and community for the most talented programmers, coders and developers in the world - YOU!<o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="COLOR: black"><FONT face="Book Antiqua"> <o:p></o:p>...
;a pure OPEN SOURCE model and bettercodes.org is and will be FREE OF CHARGE.
After fixing some major
73.
NowCoder Summer Multi-School Training Camp 2025 Hello, Codeforces!
As the official team of NowCoder (China's leading programming competition platform), we are pleased to introduce the 2025 NowCoder Summer Multi-School Training Camp! This annual event has been running for eight years. Since the summer of 2018, we have collaborated with top competitors from algorithmic competitions such as ICPC, NOI, and IOI, aiming to enhance participants' programming skills through competitions, lectures, and exchanges, and to prepare for upcoming competitions like ICPC and CCPC in the second half of the year; simultaneously, we seek to foster learning and exchange among university training teams worldwide.
<center>
<h2 style="border-bottom: 1px solid #000;">Details</h2>
</center>
1. **Schedule**. Consistent with last year, this year's training camp will consist of ten ICPC-style competitions, starting on [Tuesday, 15 July 2025<sup title="timezone offset" style="font-size:8px;" data-immersive-translate-walked="24cdac9c-eeae-41da-aef2-9dcf...
%3A+Round+10&iso=20250814T12&p1=%3A&ah=5), prepared by Nanjing Foreign Language
School (NJFLS
74.
Artificial Intelligence (AI) Artificial Intelligence (AI) is the development of computer systems capable of performing tasks that typically require human intelligence, such as learning, problem-solving, decision-making, and language understanding. AI achieves this by using algorithms and models to analyze vast amounts of data, identify patterns, and learn from experience to make intelligent decisions and predictions. Common examples include virtual assistants, recommendation systems, and AI-powered chatbots, which use AI to provide personalized experiences and automate complex processes.
language understanding. AI achieves this by using algorithms and models to
analyze vast amounts of data
75.
Tour.AI-Tourism Guide Application Based On Android And ML Implementation. ### ABSTRACT
###
The impact of digital transformation is evident in all industries and sectors, and the tourism industry is no exception where technology has disrupted the old order of things and completely reinvented the ways to explore traveling. Travel agencies and physical bookings are now almost outdated. So much that a recent survey by e marketer shows that travel-based mobile apps are the 7th most downloaded category and that 60% of smart phone users prefer travel apps for planning their leisure tours. With the help of Tour AI users for detecting different languages from the picture and then translate to the user desired language,help to find the nearby by places with the other details like phone number,map, address etc.,detect the monuments and give the details about that place just like any tour guide does and more. However, these are just the basic uses of tourism mobile apps, and more tourist services can be delivered like:
**Social** – Travel updates, reviews, picture g...
and then translate to the user desired language,help to find the nearby by
places with the other
76.
A New Way (supposedly) to answer Range Queries with Point Updates. Hello everyone :)
I am going to present a new way(I couldn't find it on the internet) to do range queries with point updates, back story and all other details later:
It is very intuitive and easy to understand, also I have included a lot of examples so please read till the end, it will be especially useful for those who are reluctant to study segment trees (I think).
You are given an array A of size N, and Q queries involving both point updates and range queries.
First we will have to do some pre-computation.I will call the precomputed structure as SST (full form later) from now.
Also, for the sake of simplicity, just assume that we are constructing the structure for sum right now, the language is going to be cpp throughout the blog.
### **Declare SST:**
~~~~~
int N = A.size() - 1;//this is assuming that the array passed is 1-indexed.
vector<vector<int>>SST(N + 1);
//It is basically a 2-D vector of size N + 1, where N is the size of the array. It is N + 1 to ha...
right now, the language is going to be cpp throughout the blog. ### **Declare
SST:** ~~~~~ int N
77.
Use(Call) Swi Prolog function in C++ <div align="justify"><br />Hi All . I have a project in my university and want to help me . I modeled a program about control traffic and avoiding collision in <b>swi prolog language</b> . (for this <a href="http://www.singaporepropertymarket.com/future_mrt_lrt_system_map.htm">map</a>) .<br /><br />I want <b>call this program in c++</b> and use it for somthing else , but i don't know and couldn't how do it ! I want some idea about how do it , or an editorial or any link about it , I hope you help me . <b>Thanks in advance</b> :)<br /></div>
modeled a program about control traffic and avoiding collision in swi prolog
language . (for this
78.
Speech Recognition There are two model:
1) Acoustic model
2) Language model
We have a dictionary full of trained voice which will be recognized.
Can anyone tell me in which model the recognition happens?
Thanks.
2) Language model
79.
Analysis of polynomial hashing Unfortunately, most derivations of the chance of polynomial hashing collision are invalid, wrong, or misleading, and finding reliable public sources with proofs is incredibly difficult. This article is a formal analysis of the method. The goal of this article is to complement well-known empirical facts with theory, provide boundaries on the probability of collision, justify common choices, and advise against certain popular parameters.
There is no code in this article, and it's mostly theoretical. It's more of a summa of everything we know about polynomial hashing in integers rather than a guide for beginners. You'll probably find something of interest still. I do, however, describe some methods of cracking hashes, which I can provide code and additional explanation for if someone asks in the comments and some general guidelines in the last section of the present article.
## Table of contents
- The concept of polynomial hashing
- Classical justification of the coprimality r...
size-bounded collision It is reasonable to improve our collision model by
analyzing the
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Problems that I Authored So Far Hi everyone! As we're reaching the end of this year and as AI becomes smarter, I'd like to write such a blog, motivated by similar blogs [by](https://codeforces.me/blog/entry/108940) [user:adamant,2024-12-22], [by](https://codeforces.me/blog/entry/108595) [user:tibinyte,2024-12-22], [by](https://codeforces.me/blog/entry/113093) [user:antontrygubO_o,2024-12-22], [by](https://codeforces.me/blog/entry/113720) [user:wuhudsm,2024-12-22], [by](https://codeforces.me/blog/entry/113687) [user:xiaowuc1,2024-12-23], [by](https://codeforces.me/blog/entry/113213) [user:jqdai0815,2024-12-23], [by](https://codeforces.me/blog/entry/118825) [user:TheScrasse,2024-12-23] and [by](https://codeforces.me/blog/entry/127391) [user:satyam343,2024-12-22].
I am a member of the [SUA Programming Contest Problem Setter Team](https://sua.ac), so most of the problems I authored are for the onsite contests prepared by our team. I would like to thank all our team members for discussing the problems with me, ...
://esolangs.org/wiki/Chicken) language. | | 3 | [Edge to the
Root](https://pintia.cn/problem-sets/91827364500
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A Time Complexity Guide **Introduction**
Often in Competitive Programming, we have to choose between multiple algorithms/ approaches for a problem. How do we decide which algorithm is better and which algorithm to go for? Runnning an algorithm comes at the cost in the form of time taken or memory consumed. In this blog, we will try to compare algorithms or approaches based on their Time Complexity, which simply put is the time taken by them to run.
So how do we compare the algorithms? Do we calculate the exact time taken by them to run? Or do we try to predict the time taken based on our input? These approaches to calculate Time Complexity can be called as _Experimental Analysis_ and _Theoretical Analysis_ respectively.
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**=========================================================================================================**
**Big O Notation**
The Big O Notation ($O()$) provides a mathematical notation to understand the complexity of an algorithm or to represent the complexity of an a...
analyze algorithms based on recurrence relations. Recurrence relation is a
mathematicalmodel that helps
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UTPC April Fool's Contest 2026 Editorial The [prophecy](https://codeforces.me/blog/entry/127899) is true: "Hopefully we will have many more years :)"
[A — Captcha](https://codeforces.me/gym/106452/problem/A)
Author: [user:m7a1g5i8k8a1r4p0,2026-04-02]
<spoiler summary="Solution">
Just print the number of circles in the image. There are `7` if you include the circles in `i` and `?`.
</spoiler>
<spoiler summary="Feedback">
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Best Problem Ever
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Incredible Problem
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Amazing Problem
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Great Problem
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Good Problem
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[B — Right or Wrong?](https://codeforces.me/gym/106452/problem/B)
Author: [user:m7a1g5i8k8a1r4p0,2026-04-02]
<spoiler summary="Solution">
The title implies that you should check if the 3 numbers are "right" or not. You can do this by checking that $a$, $b$, and $c$ form the side lengths of a right triangle, with $c$ as the hypotenuse.
</spoiler>
<spoiler summary="Feedback">
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Best Prob...
your language to Russian. To solve Pollux's problem
Tutorial of UTPC April Fools Contest 2026
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replica watches In 1905 Hans Wilsdorf and his brother-in-law Alfred Davis founded "Wilsdorf and Davis" in London. Their main business <a href=http://www.growwatches.com/panerai.html>panerai replica watches</a> at the time was importing Hermann Aegler's Swiss movements to England and placing them in quality cases made by Dennison and others. These early wristwatches were sold to jewellers, who then put their own names on the dial. The earliest watches from Wilsdorf <a href=http://www.growwatches.com/chanel.html>fake chanel watches</a> and Davis were usually hallmarked "W&D" inside the caseback.In 1908 Wilsdorf registered the trademark "Rolex" and opened an office in La Chaux-de-Fonds, Switzerland. The company name "Rolex" was registered on 15 November 1915. The word was made up, and its origin is obscure. Wilsdorf was said to want his watch brand's name <a href=http://www.growwatches.com/breguet.html>breguet watches</a> to be easily pronounceable in any language. One story, never confirmed by Wilsdorf,...
>breguet watches to be easily pronounceable in any language. One story, never
confirmed by Wilsdorf
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Codeforces Round 1058 Editorial Thanks for the participation! We hope you enjoyed the contest.
<spoiler summary="Rate the contest!">
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<strike>The solution codes will be added shortly after the system tests are finished.</strike> They have been added.
[problem:2160A]
Problem Credit: [user:Proof_by_QED,2025-10-12]
<spoiler summary="Rate the problem!">
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<spoiler summary="Solution">
First, let $m=\operatorname{mex}(A)$. We can ignore all elements that are greater than $m$. This is because since $m$ is the mex, $m$ does not appear in $A$, and consequently it also cannot appear in any of the partitions. Thus, which of the partitions each element goes to does not matter.
Now, let's consider the n...
. - We can model another DP by swapping the places of cost and index, and this
new DP will only have at
Tutorial of Codeforces Round 1058 (Div. 1)
Tutorial of Codeforces Round 1058 (Div. 2)
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