[Hackerearth] Make Palindrome

 

Problem Link    : Make Palindrome
Category        : Add Hoc
Contest         : DSA Coding Contest - January '24

#include "bits/stdc++.h"
using namespace std;
#define int     long long int
#define endl    '\n'
 
signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr); cout.tie(nullptr);
    cout.precision(12);
 
    bool FILEIO = 1;
    if (FILEIO and fopen("in.txt", "r")) {
        freopen("in.txt", "r", stdin);
        freopen("out.txt", "w", stdout);
    }
 
    int tc;
    cin >> tc;
    for (int tcase = 1; tcase <= tc; tcase++) {
        int n; string s;
        cin >> n >> s;
        vector<int> counters(26);
        for (char ch : s) {
            counters[ ch - 'a' ]++;
        }
        int odds = 0;
        for (int x : counters) {
            odds += x % 2;
        }
        cout << max(0LL, odds - 1) << endl;
    }
}