1006D - Two Strings Swaps - CodeForces Solution

#include <bits/stdc++.h>
using namespace std;

int main() {
    cout.sync_with_stdio(0);
    cin.tie(0);

    int n; cin >> n;
    string a,b; cin >> a >> b;
    int res = 0;
    for (int i = 0, j = n-1; i <= j; i++, j--) {
        if (i == j) {
            if (a[i] != b[i]) res += 1;
            continue;
        }
        int cnt[26], ai = a[i]-'a', aj = a[j]-'a', bi = b[i]-'a', bj = b[j]-'a';
        cnt[ai] = 0, cnt[bi] = 0, cnt[aj] = 0, cnt[bj] = 0;
        cnt[ai]++, cnt[bi]++, cnt[aj]++, cnt[bj]++;
        if (cnt[bi] == 1 && cnt[bj] == 1) res+=2;
        else if (cnt[bi] > 1 && cnt[bj] > 1) {
            if (cnt[ai] > 1 && cnt[aj] > 1) continue;
            else res += 1;
        }
        else res += 1;
    }
    cout << res << endl;

    return 0;
}