Hi Codeoforces, Where(websites) do most of the USA coders practice and participate in contests?

I know binary search but most of the time I gets confused how to find mid index and what to return low or high.
There are two while loop conditions:
1. while(low<high)
2. while(low<=high)
There are two ways to find mid element:
1. mid = (low+high)/2
2. mid = (low+high+1)/2
And then depending on the required condition we do low = mid+1 and right = mid or low = mid and right = mid-1 or something else. I know it's something keeping low always as our answer and returning that after while loop breaks and if high is always possible answer we return high. But I don't know clearly what to do when. Is there any logical way to do this stuff, I have try some combinations before getting right pair of conditions.
Thanks in advance.

What are benifits/advantages of reaching regional round in ICPC. We have to pay registration fees (Amritapuri). Then why are people are excited to get shortlisted as only top 2-3 teams are going to be selected for further rounds/world finals?

Any Idea how many teams will get selected in Gwaliar-Pune regionals and Kanpur-Mathura Regionals. These regions are not conducting any prelimry test and contestants will directly qualify for word finals. So, usually how much teams qualify for world finals. Is it even worth giving ICPC this year, as there is very slim chance(or 0 for me) for getting into world finals and there nothing much else to achieve.

Can somebody recommend how to solve SPOJ problems or some must do problems or problems in importance wise sorted order? Is it even worth to solve SPOJ probelems?

There are many range query algorithms such as
1. Segment Trees
2. Square Root Decomposition
3. Fenwick Tree
4. Mo's Algorithm
5. Heavy Light Decomposition
6. Sparse Table
Can anybody please tell me or give link to any previous already published blog (I couldn't find any) regarding which algo to use when? Which is most important among them all?

According to me following are the standard algorithms:
1. DP / Greedy
2. DFS/BFS
4. Sorting/Binary Search/ Data Structures like maps and sets 4. Maths (Basic not FFt or something)
Although these algorithms are sufficient to become candidate master and 5 star if one has speed and accuracy but I believe I will need to learn some advanced algorithms to further increase the level. Can somebody please share the algorithms which are most occurring in 4th/5th question of Codeforces Div 2 round and 2nd/3rd question of codechef div 1 cookoff.

iterator to any element in set belongs to address or value in c++? For example, my set is {1,2,3,4,5} and *it =3; So, here it is pointing to 3 or address where three is stored? I have tried it in my compiler, even after deleting 3 from set *it is still showing 3. How is this possible? And when I did it-- *it shows 2. And after it++, it directly jumps to 4. I have searched over internet but didn't find anything satisfying.

I want to practice questions which are heavy implementation based, making structs/classes and all. Can anybody list some questions which they have have done in past involving lot of implementation.

Suppose there is an array of integers representing values of blocks. We have to create towers such that (i)th block in tower has value less than or equal to (i-1)th.
a. Calculate the height of tallest tower.
b. Calculate the minimum number of towers to equip all the blocks.
Obviously, the the answer of first part is longest decreasing array. I am not sure about second part but according to me the answer will the longest strictly increasing array.
Correct me if I am wrong.

Sometimes when I do question of around 10^7 operations, I don't need to use fast io but the questions which can be solved with 10^5 operations gets TLE without using fast io. Is there some trick to guess when do we need to use fast io or it we have to use it in every question.

Hello Codeforces!
I am ready for lot of downvotes but I want a serious advice.
I am pre-final year student in Tier 1/Tier 2 college(new IIT, consider it in whichever tier you want). I have done internship in a small start-up. Now I have two options, can do one more internship in relatively good company(obviously not in Amazon/Microsoft) or can do lot of coding, enhance my coding skills and core subject knowledge.
Which option will be more beneficial for my placements, a good internship or coding skills.

For those who will downvote, I have no problem with you but please give me advise before doing that.
I am sure lot of students may have same question.

Tomorrow is action packed full house
Tight you seat belts for back to back contests
1. LeetCode(8:00-9:30)
2. KickStart(9:30-12:30)
3. Atcoder (4:30-6:30)
4. Codeforces (6:30-8:30)
5. Cook-Off (9:30-midnight)
Have fun day XD.

I have solved top 100 liked questions on leetcode. What should I do now. I don't have subscription to do company wise questions. Can somebody recommend some other list to do. I personally don't think those 100 questions are enough.

I remembered my professor explaining popular edit distance question using divide and conquer approach but don't remember exactly how. Do somebody know this approach or know that this approach can't exist.
His notes link: https://drive.google.com/file/d/1UISiTL7J3VKXfE43h1lDLld6Id26jF8j/view?usp=sharing
Start reading from page 6.

I have observed that users who stopped participating in contest does not have global and country rank. Can somebody tell what is threshold for such time, like I can go 6 month contest free and still have global rank?

Do somebody know when will code nation declare result or cutoff questions. I did first 3 questions. How much you guyz did? Last time those who did 3 were called for interviews.