Sukat

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


int main(){
    string s; cin >> s;
    int n = s.size();
    vector<int> counts(26);
    for(int i = 0; i < n; i++) counts[s[i]-'A'] += 1;
    set<pair<int, char>> v;
    for(int i = 0; i < 26; i++){
        if(counts[i] > 0) v.insert(make_pair(counts[i], 'A' + i));
    }

    vector<string> res;
    while(v.size() > 1){
        pair<int, char> p1 = *(--v.end());
        v.erase(--v.end());
        pair<int, char>  p2 = *(--v.end());
        v.erase(--v.end());
        string t = "";
        t += p1.second;
        t += p2.second;
        res.push_back(t);
        if(p1.first > 1) v.insert(make_pair(p1.first - 1, p1.second));
        if(p2.first > 1) v.insert(make_pair(p2.first - 1, p2.second));
    }
    cout << res.size() << "\n";
    for(string ss : res) cout << ss << "\n";

    /*for(int i = 0; i < 26; i++){
        for(int j = i+1; j < 26; j++){
            int r = min(v[i].first, v[j].first);
            string t = "";
            t += v[i].second;
            t += v[j].second;
            for(int k = 0; k < r; k++) res.push_back(t);
            v[i] = make_pair(v[i].first - r, v[i].second);
            v[j] = make_pair(v[j].first - r, v[j].second);
        }
    }
    cout << res.size() << "\n";
    for(string sss : res) cout << sss << "\n";*/
    // ZZZZZZZZZZZZAAABHJSAKDOOOOOOOOO

    // AAAAABBBBCCC
    /*
    
    5 4 3
    4 3 3
    3 2 3
    2 2 2
    1 2 1
    1 1


    */
}

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