Monistus

input/code.cpp: In function 'int main()':
input/code.cpp:12:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   12 |   while (idx != s.size()) {
      |          ~~~~^~~~~~~~~~~

#include <bits/stdc++.h>
#include <cctype>

using namespace std;

int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  string s;
  cin >> s;
  int idx = 0;
  while (idx != s.size()) {
    if (isdigit(s[idx])) {
      string copy = s.substr(idx + 1, s[idx] - '0');
      s.replace(idx, 1, copy);
      // cout << s << '\n';
    } else {
      idx++;
    }
  }
  cout << s;
}

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 1, 2

Verdict: ACCEPTED

Test 3

Group: 1, 2

Verdict: ACCEPTED

Test 4

Group: 1, 2

Verdict: ACCEPTED

Test 5

Group: 1, 2

Verdict: ACCEPTED

Test 6

Group: 1, 2

Verdict: ACCEPTED

Test 7

Group: 1, 2

Verdict: ACCEPTED

Test 8

Group: 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 2

Verdict: ACCEPTED

Test 11

Group: 2

Verdict: ACCEPTED

Test 12

Group: 2

Verdict: ACCEPTED

Test 13

Group: 2

Verdict: ACCEPTED

Test 14

Group: 2

Verdict: TIME LIMIT EXCEEDED