Sukat

#include <bits/stdc++.h>

using namespace std;

int main() {
    const int Z = 30;
    string str;
    cin >> str;
    
    vector<int> sukat;

    for (int i = 0; i < (int) str.length(); i++) {
        sukat.push_back((int) str[i]);
    }
    sort(sukat.begin(), sukat.end());

    int s1[Z] = { 0 };
    int s2[Z] = { 0 };
    int c1 = 0;
    int c2 = 0;

    int last = -1;
    bool g = true;
    for (int i = 0; i < (int) sukat.size(); i++) {
        //cout << sukat[i] << " ";
        int c = ((int) sukat[i]) - 65;
        if (c != last) {
            g = c1 < c2;
            last = c;
        }
        if (g) {
            s1[c]++;
            c1++;
        } else {
            s2[c]++;
            c2++;
       }
    }
    
    //cout << endl;

    //cout << s1[0] << s1[1] << s1[2] << endl;
    //cout << s2[0] << s2[1] << s2[2] << endl;

    vector<pair<char, char>> res;

    while (c1 > 0 && c2 > 0) {
        int max1 = -1;
        int index1 = -1;
        for (int i = 0; i < Z; i++) {
            if (s1[i] > max1) {
                index1 = i;
                max1 = s1[i];
            }
        }
        int max2 = -1;
        int index2 = -1;
        for (int i = 0; i < Z; i++) {
            if (s2[i] > max2) {
                index2 = i;
                max2 = s2[i];
            }
        }

        //cout << "i1: " << index1 << " i2: " << index2 << endl;

        int a = min(max1, max2);
        s1[index1] -= a;
        s2[index2] -= a;
        c1 -= a;
        c2 -= a;
        
        for (int i = 0; i < a; i++) {
            res.push_back({ (char) (index1 + 65), (char) (index2 + 65)});
        }
    }

    cout << res.size() << "\n";
    for (int i = 0; i < (int) res.size(); i++) {
        cout << res[i].first << res[i].second << "\n"; 
    }
}

Test 1

Group: 1, 2, 3

Verdict: ACCEPTED

Test 2

Group: 1, 2, 3

Verdict: ACCEPTED

Test 3

Group: 1, 2, 3

Verdict: ACCEPTED

Test 4

Group: 1, 2, 3

Verdict: WRONG ANSWER

Test 5

Group: 1, 2, 3

Verdict: ACCEPTED

Test 6

Group: 1, 2, 3

Verdict: WRONG ANSWER

Test 7

Group: 1, 2, 3

Verdict: ACCEPTED

Test 8

Group: 2, 3

Verdict: WRONG ANSWER

Test 9

Group: 2, 3

Verdict: ACCEPTED

Test 10

Group: 2, 3

Verdict: WRONG ANSWER

Test 11

Group: 2, 3

Verdict: WRONG ANSWER

Test 12

Group: 2, 3

Verdict: WRONG ANSWER

Test 13

Group: 2, 3

Verdict: WRONG ANSWER

Test 14

Group: 2, 3

Verdict: WRONG ANSWER

Test 15

Group: 3

Verdict: WRONG ANSWER

Test 16

Group: 3

Verdict: ACCEPTED

Test 17

Group: 3

Verdict: WRONG ANSWER

Test 18

Group: 3

Verdict: ACCEPTED

Test 19

Group: 3

Verdict: WRONG ANSWER

Test 20

Group: 3

Verdict: WRONG ANSWER

Test 21

Group: 3

Verdict: WRONG ANSWER