Sukat

#include<bits/stdc++.h>
using namespace std;
 
void init_code(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    #ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    #endif 
}
 
void solve() {
   string str;
   cin >> str;
 
   int n = str.size();
 
   vector<pair<int, int>> tmp(26);
 
   for (int i = 0; i < n; ++i) {
      int x = str[i] - 'A';
 
      tmp[x].first++;
      tmp[x].second = x;
   }

   multiset<pair<int, int>> s;
   for (auto i : tmp) {
      s.insert(i);
   }

   set<string> ans;

   while (1) {
      if (s.size() <= 1) {
         break;
      }

      pair<int, int> a = *s.rbegin(), b = *s.begin();
      
      //cout << a.first << ' ' << b.first << '\n';

      s.erase(a);
      s.erase(b);

      string t = "";
      char x = 'A' + a.second, y = 'A' + b.second;
      t += x; t += y;
 
      int k = b.first;
 
      for (int i = 0; i < k; ++i) {
         ans.insert(t);
      }

      s.insert({a.first - b.first, a.second});
   }

   cout << ans.size() << '\n';
   for (auto i : ans) {
      cout << i << '\n';
   }
}
 
int main() {
   init_code();
   solve();
   return 0;
}

Test 1

Group: 1, 2, 3

Verdict: ACCEPTED

Test 2

Group: 1, 2, 3

Verdict: ACCEPTED

Test 3

Group: 1, 2, 3

Verdict: WRONG ANSWER

Test 4

Group: 1, 2, 3

Verdict: WRONG ANSWER

Test 5

Group: 1, 2, 3

Verdict: WRONG ANSWER

Test 6

Group: 1, 2, 3

Verdict: ACCEPTED

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: WRONG ANSWER

Test 19

Group: 3

Verdict: WRONG ANSWER

Test 20

Group: 3

Verdict: WRONG ANSWER

Test 21

Group: 3

Verdict: WRONG ANSWER