【題解】AtCoder ABC 171D – Replacing

#include <iostream>
using namespace std;

int n, a, cnt[100005], q, b, c;
long long ans;

int main() {
    cin >> n;
    for (int i = 0; i < n; i++){
        cin >> a;
        cnt[a]++;
        ans += a;
    }
    cin >> q;
    for (int i = 0; i < q; i++){
        cin >> b >> c;
        ans += (c-b) * cnt[b];
        cnt[c] += cnt[b];
        cnt[b] = 0;
        cout << ans << "\n";
    }
}