I was trying to solve the question B2 — Social Network (hard version). Question Link: https://codeforces.com/contest/1234/problem/B2

I first tried to code the solution using queue and unordered_map. But that gave me TLE. But when I used a map in place of unordered_map, the solution got accepted. Unordered_map does not keep the keys in a sorted format. Then why did an implementation using maps work better? Please guide me on this.

Thanks in advance!!