Sukat

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

 struct C{
        char c;
        ll cnt;
        friend auto operator<=>(C a, C b) { return a.cnt <=> b.cnt;}
    };

int main() {
    string sukat;
    cin >> sukat;

    map<char, ll> cnt;
    for (char c: sukat) {
        cnt[c] += 1;
    }

   

    vector<string> ans;
    vector<C> counts;
    for (auto x: cnt) {
        counts.push_back({x.first, x.second});
    }
    
    while(counts.size() > 1) {
        ranges::sort(counts, [](auto x, auto y) {
        return x.cnt < y.cnt;
    });
        auto& e = counts.front();

        priority_queue<C> q(counts.begin() + 1, counts.end());
        while (e.cnt > 0) {
            auto top = q.top();
            q.pop();
            top.cnt--;
            e.cnt--;
            if (top.cnt > 0) q.push(top);
            ans.push_back(string(1, e.c) + top.c);
        }
        counts.clear();
        while (!q.empty()) {
            counts.push_back(q.top());
            q.pop();
        }
    }

    cout << ans.size() << "\n";
    for (auto& s: ans) {
        ranges::sort(s);
    }
    ranges::sort(ans);

    for (auto& s: ans) {
        cout << s << "\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: ACCEPTED

Test 14

Group: 2, 3

Verdict: ACCEPTED

Test 15

Group: 3

Verdict: ACCEPTED

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: ACCEPTED

Test 21

Group: 3

Verdict: ACCEPTED