Sukat

input/code.cpp: In function 'int main()':
input/code.cpp:50:14: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   50 |     for(auto [x, y] : ans)
      |              ^
input/code.cpp:26:17: warning: unused variable 'countt' [-Wunused-variable]
   26 |     ll l, i, j, countt = 0;
      |                 ^~~~~~

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector <ll> vl;
typedef vector <vl> vvl;
typedef pair <ll, ll> pl;
typedef vector <pl> vpl;
typedef vector <bool> vb;

const ll inf = 1e18;
const ll mod = 1e9 + 7;
const ll nmax = 1e6;

#define fi first
#define se second
#define mp make_pair
#define pb push_back

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);

    string s;
    vpl a(26, {0, 0}), ans;
    ll l, i, j, countt = 0;
    cin >> s;
    l = s.length();
    for(i = 0; i < l; i++)
        a[s[i] - 'A'].fi++;
    for(i = 0; i < 26; i++)
        a[i].se = i;
    sort(a.begin(), a.end(), greater<pl>());
    i = 0, j = 1;
    while(i < 26 && j < 26)
    {
        while(a[i].fi > 0 && a[j].fi > 0)
        {
            a[i].fi--;
            a[j].fi--;
            ans.pb({a[i].se, a[j].se});
        }
        if(a[i].fi == 0)
            i = max(i, j) + 1;
        else
            j = max(i, j) + 1;
    }

    cout << ans.size() << "\n";
    for(auto [x, y] : ans)
        cout << char(x + 'A') << char(y + 'A') << "\n";


    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: 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