you can practice topic wise and difficulty wise sorting on this Atcoder Tags to get better in future.

This year's hardest B

wtf

Harder version of problem F. https://www.quora.com/What-is-the-approach-to-solve-the-SPOJ-problem-QTREE4

D is so hard for me OMG

F: https://www.luogu.com.cn/problem/P2056 and SPOJ QTREE4

actually, it was only in the last two minutes that I realized I could avoid precision issues by squaring.

Can someone explain D, I got the part that the first time a cell becomes black, will be black at end. But how to find that?

Can someone explain me the 3rd test case of B. I mean Mathematically drew it on a paper. The answer is A yes. But the test case shows No. Why???? x1 y1 r1 x2 y2 r2 1 2 5 3 2 1

Can someone help me why in editorial of C we are doing operation for first time and then we are applying the multi source BFS?

The B was quite challenging with the its slight edge case of circle inside circle.

Why everything about ds? I'm not good at ds so i think it isn't interesting :(

D was interesting . But couldn't implement it.

F is a joke.

HAVE LOTS OF SAME PROBLEMS

AtCoder Qtree Contest = =

F I have a simpler O(nsqrtn) approach
Consider sqrt divide and conquer, dividing the points into two categories: static points and dynamic points (those that never change and those that do). First, preprocess the maximum dis of the global static points and the maximum dis from each point to the static black point, denoted as m_i. Within each block, the answer to modifying a point has three possibilities: static point — static point (which is the global dis), dynamic point — static point (which is the maximum m_i of the dynamic points within the current block), and dynamic point — dynamic point (which is similar to the diameter of a tree, requiring two DFS simplifications). The complexity is sqrtn. However, testing revealed that recursive DP can be bottlenecked; using an array is much faster.

I would like to ask if there are any issues with the code for question B.

#include <iostream>
#include <cmath>
using namespace std;
typedef long long ll;

int main() {
    int T;
    cin >> T;
    while (T--) {
        ll X1, Y1, R1, X2, Y2, R2;
        cin >> X1 >> Y1 >> R1 >> X2 >> Y2 >> R2;

        ll dx = X1 - X2;
        ll dy = Y1 - Y2;
        ll d_sq = dx * dx + dy * dy;

        ll sumR = R1 + R2;
        ll sumR_sq = sumR * sumR;

        ll diffR = abs(R1 - R2);
        ll diffR_sq = diffR * diffR;

        if (d_sq >= diffR_sq && d_sq <= sumR_sq)
            cout << "Yes\n";
        else
            cout << "No\n";
    }
    return 0;
}

Problem F lies in dynamically modifying node states (black/white coloring) and querying the diameter of connected black components in real-time.

(I use gemini to translate these words)

This user jiziyang may have violated the rules prohibiting the use of generative AI during contests. Here are some highly suspicious patterns observed in their recent contest submissions:

there are excessive and unnatural comments within the code:

ABC 460 C (This is a very simple problem, yet the comments use fancy formatting symbols, which is a strong indicator of AI-generated output.)

ABC 460 E (Contains a massive wall of boilerplate-like comments.)

ABC 459 D, ABC 459 B, (Features a bizarre comment block at the very top of the code. Strangely, in ABC 459, only problem B has this pattern.)

ABC 458 F, ABC 458 D, ABC 457 B, ABC 456 C, ABC 456 E, ABC 456 G, (While his registered country / region is shown as Taiwan, the code comments are written in Simplified Chinese, which is predominantly used in China.)

ABC 456 B (Occasionally, the comments suddenly switch to flawless, textbook English.)

ABC 456 G (Solved problem G at an unnaturally blistering speed.)

In fact, I have been keeping an eye on this account ever since ABC 456, and these constant anomalies seem too glaring to ignore. What do you think?

a<c<e<b<d,so I solved abce