2295. Replace Elements in an Array

You are given a 0-indexed array nums that consists of n distinct positive integers. Apply m operations to this array, where in the ith operation you replace the number operations[i][0] with operations[i][1].

It is guaranteed that in the ith operation:

• operations[i][0] exists in nums.
• operations[i][1] does not exist in nums.

Return the array obtained after applying all the operations.

class Solution {
public:
    vector<int> arrayChange(vector<int>& A, vector<vector<int>>& O) {
        unordered_map<int, int> mp;
        int n = A.size(), m = O.size();
        for(int i = 0; i < n; i++) {
            mp[A[i]] = i;
        }
        
        for(auto o : O) {
            int f = o[0], t = o[1];
            int idx = mp[f];
            A[idx] = t;
            mp.erase(f);
            mp[t] = idx;
        }
        
        return A;
    }
};