question link -> https://mirror.codeforces.com/contest/1490/problem/F submission with unordered map -> https://mirror.codeforces.com/contest/1490/submission/221004592 submission with ordered map -> https://mirror.codeforces.com/contest/1490/submission/221004710









Read this block https://mirror.codeforces.com/blog/entry/62393
Because unordered_map works using hashing concept, and tester can write a particular test case according to hash function which cause more collision and hence cause worst time complexity to find a place(O(n)) to fit a particular element.