Sukat

input/code.cpp: In function 'int main()':
input/code.cpp:14:23: warning: comparison of integer expressions of different signedness: 'int' and 'size_t' {aka 'long unsigned int'} [-Wsign-compare]
   14 |     for (int i = 0; i < strlen(s); i++) {
      |                     ~~^~~~~~~~~~~
input/code.cpp:42:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<char, char> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   42 |     for (int i = 0; i < res.size(); i++) {
      |                     ~~^~~~~~~~~~~~
input/code.cpp:13:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   13 |     scanf("%s", s);
      |     ~~~~~^~~~~~~~~

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

#define CHARS 26

int nums[CHARS];
char s[1000000];

int main()
{
    vector<pair<char, char>> res;

    scanf("%s", s);
    for (int i = 0; i < strlen(s); i++) {
        char c = s[i];

        int a = c - 'A';
        nums[a]++;
    }

    for (int i = 0; i < CHARS - 1; i++) {
        for (int j = i + 1; j < CHARS && nums[i] > 0; j++) {
            if (nums[j] == 0) {
                continue;
            }

            int n = min(nums[i], nums[j]);
            nums[i] -= n;
            nums[j] -= n;
            for (int k = 0; k < n; k++) {
                res.push_back(make_pair(i + 'A', j + 'A'));
            }
        }
    }

    for (int i = 0; i < CHARS; i++) {
        //cerr << nums[i] << endl;
    }

    cout << res.size() << endl;

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

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