Here is the solution for Codeforces 1325E which is a number theory and graphs problem.
Here is the problem statement: https://codeforces.com/problemset/problem/1325/E
Here is my solution (the code presented in the video):
https://codeforces.com/contest/1325/submission/73833634
For more help with USACO contests, visit https://www.vplanetcoding.com/?sl=yt1325E_jul252020
