Hi. In this comment, there is a formula to count the number of graphs with i vertices having cycle length j. Which is Can somebody explain the formula ?. I understand that first part. We choose j vertices from i vertices to form a cycle. Then we permute them. which is j!. But I could not figure out the rest.

Thank you for your time in advance.

Hi. Today i tried to solve 598F - Длина разреза. There is an editorial. However as a pupil i did not get anything from that. So any idea would be appreciated how to solve it. Thank you in advance.

Hi. I have following problem. Yesterday I tried to solve this problem The same code with emplace_back does not pass the system test. However the same code with push_back passes the system test. So my question is: What is happening here ? Link to the submission with push_back Link to the submission with emplace_back