Monistus

#include <iostream>

int main() {
    std::string input;
    std::cin >> input;
    int i = 0;
    int l = input.length();
    while(i < l){
        if(isdigit(input[i])){
            int num = input[i] - '0';
            std::string mid = input.substr(i+1, num);
            input = input.replace(i, num+1, mid+mid); 
            i-=1;
        }
        i += 1;
    }
    std::cout << input << "\n";
 
    return 0;
}

Test 1

Group: 1, 2

Verdict: WRONG ANSWER

Test 2

Group: 1, 2

Verdict: ACCEPTED

Test 3

Group: 1, 2

Verdict: WRONG ANSWER

Test 4

Group: 1, 2

Verdict: WRONG ANSWER

Test 5

Group: 1, 2

Verdict: WRONG ANSWER

Test 6

Group: 1, 2

Verdict: WRONG ANSWER

Test 7

Group: 1, 2

Verdict: WRONG ANSWER

Test 8

Group: 2

Verdict: WRONG ANSWER

Test 9

Group: 2

Verdict: WRONG ANSWER

Test 10

Group: 2

Verdict: WRONG ANSWER

Test 11

Group: 2

Verdict: ACCEPTED

Test 12

Group: 2

Verdict: WRONG ANSWER

Test 13

Group: 2

Verdict: TIME LIMIT EXCEEDED

Test 14

Group: 2

Verdict: TIME LIMIT EXCEEDED