Hello CF community,

I was solving problem 3 (Balancing Tree) from last USACO round, when I encountered some sussy behaviour. I submited my code, which in local testing passed both the examples, but upon grading, it passed only 1, the other one being WA. I have locally tested another subtask, with the same result (local testing led to a good result, but WA on grading).

Here is the code and here is the problem link. Hope I was clear enough with my issue and thanks in advance!

Have a good day!

Hello CF community,

I just stumbled upon this weird (at least for me) behaviour. I was trying to solve 1605C - Доминантный характер, I set the compiler to C++ 20 and sent this code 135233345 but got C.E. for whatever reason. Then I thought of switching back to C++ 17 and this time I got accepted 135233454 (Note that it is the same code).

Can someone tell me why this is happening?

Hello again Codeforces community!

I'm back with another problem, which I'm not able to solve. I don't have any link, it isn't from any site.

You are given a permutation of size N and Q queries. In 1 query, you are given x and y, and you need to swap the values on position x and y (formally, you need to swap v[x] and v[y]). After every query, you have to print the number of prefixes of the permutation, that are permutations.

For example, if you have array A = [2, 1, 3, 4], the answer is 3 (permutation at index 2, 3 and 4).

Example:

Input:
4 3
1 4 3 2
2 3
2 4 1 2

Output:

2 3 2

1 <= N, Q <= 100000.

The only approach I could come up with was brute force. Could anyone help me?

Hi Codeforces Community! I have been struggling with a problem that I find quite hard. Unfortunately, I don't have a link to the English version. I will try to make a short description of it.

You have 2 strings A and B, of length N and M. The strings contain only lowercase Latin letters. For every substring S of B, you have to find the length of the longest common prefix of A and S. Print the sum of these lengths.

1 <= N, M <= 2 000 000
Time Limit: 1.5 seconds
Memory Limit: 32768 kbytes

Examples:

If A = aa, B = abaa, then the answer is 8. If A = aab, B = acaabada, then the answer is 32.

I tried an approach with hashes and binary searching, but I got TLE. Is there any faster way to solve this problem? Thanks in advance.

P.S.: I will explain my approach, if needed.

Hope you'll have a great day, Protroll