Hello guys I'm trying to be good at counting using combinatorics.

Can anyone recommend some tutorials/problems for me ... Thanks in advance and RAMADAN KAREEM

Hello every one ,wish you are doing great .... can any one explain how does this code doesn't got TLE ? https://codeforces.com/contest/246/submission/79394388

My idea is:

1-I'm storing all nodes in subtree of u at depth x using dfs time.

2- In every query first I check if I've encountered a query asking about the same nodes then I print answer as I save the ans of every query else then I iterate over all strings at depth d[i] + x at subtree of u and find number of distinct strings using set.

thanks in advance