Hi,

I have just started with learning graphs and was doing a question which involved basic dfs. While doing it, I was getting TLE when I was using iterative dfs and when I only changed the dfs from iterative to recursive, the solution got accepted. Since the time complexity of both the methods are same, the only reason I could think of is the time taken to push and pop in the stack, but I didn't think the difference would be this huge.

These are the links:

Problem: https://mirror.codeforces.com/contest/771/problem/A

iterative solution: https://mirror.codeforces.com/contest/771/submission/87812642

recursive solution: https://mirror.codeforces.com/contest/771/submission/87812583

I am baffled by the difference in the runtime of the 2 solutions. If anyone knows a reason for this, please help me :)