Sukat

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

int brute(string s) {
    sort(s.begin(),s.end());
    int n = s.size();
    int cnt = 0;
    do {
        int cur = 0;
        for (int i = 0; i < n-1; i += 2) {
            if (s[i] != s[i+1])
                ++cur;
        }
        cnt = max(cnt,cur);
    } while (next_permutation(s.begin(),s.end()));
    return cnt;
}

signed main() {
    string s;
    cin >> s;
    int n = s.size();

    vector<pair<int,char>> v(27);

    for (int i = 0; i < n; ++i) {
        v[s[i]-'A'].second = s[i];
        ++v[s[i]-'A'].first;
    }

    sort(v.rbegin(),v.rend());

    int i = 0;

    vector<string> ans;
    for (int j = 1; j < 26; ++j) {
        if (v[i] > v[j]) {
            for (int k = 0; k < v[j].first; ++k) {
                string s1 = "";
                s1 += v[i].second;
                s1 += v[j].second;
                ans.push_back(s1);
            }
            v[i].first -= v[j].first;
            v[j].first = 0;
        }
        else {
            for (int k = 0; k < v[i].first; ++k) {
                string s1 = "";
                s1 += v[i].second;
                s1 += v[j].second;
                ans.push_back(s1);
            }
            v[j].first -= v[i].first;
            v[i].first = 0;
            while (!v[i].first && i < 26 && i != j)
                ++i;
        }
    }

    cout << ans.size() << '\n';
    for (auto u : ans)
        cout << u << '\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: ACCEPTED

Test 5

Group: 1, 2, 3

Verdict: ACCEPTED

Test 6

Group: 1, 2, 3

Verdict: ACCEPTED

Test 7

Group: 1, 2, 3

Verdict: ACCEPTED

Test 8

Group: 2, 3

Verdict: ACCEPTED

Test 9

Group: 2, 3

Verdict: ACCEPTED

Test 10

Group: 2, 3

Verdict: ACCEPTED

Test 11

Group: 2, 3

Verdict: ACCEPTED

Test 12

Group: 2, 3

Verdict: ACCEPTED

Test 13

Group: 2, 3

Verdict: WRONG ANSWER

Test 14

Group: 2, 3

Verdict: ACCEPTED

Test 15

Group: 3

Verdict: WRONG ANSWER

Test 16

Group: 3

Verdict: ACCEPTED

Test 17

Group: 3

Verdict: ACCEPTED

Test 18

Group: 3

Verdict: ACCEPTED

Test 19

Group: 3

Verdict: ACCEPTED

Test 20

Group: 3

Verdict: WRONG ANSWER

Test 21

Group: 3

Verdict: ACCEPTED