Monistus

#include <iostream>
#include <vector>
#include <utility>
#include <algorithm>
#include <limits.h>
#include <stack>

using namespace std;

typedef long long ll;

void update_stack(stack<int>& st, int n) {
    if (st.empty())
        return;
    int x = st.top();
    st.pop();
    update_stack(st, n);
    st.push(x + n);
}

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);

    string s;
    cin >> s;

    stack<int> stack;

    for (int i = s.size() - 1; i >= 0; i--) {
        int l = s[i] - '0';
        if (l > 0 && l < 10) {
            stack.push(i);
        }
    }

    while (!stack.empty()) {
        int i = stack.top(); stack.pop();
        int l = s[i] - '0';

        //cout << stack.size() << " " << i << " " << l << endl;

        string ss = s.substr(i + 1, l);
        s.erase(i, 1);
        s = s.insert(i, ss);

        update_stack(stack, ss.size() - 1);

        for (int j = ss.size(); j >= 0; j--) {
            l = ss[j] - '0';
            if (l > 0 && l < 10) {
                stack.push(j + i);
            }
        }
    }

    cout << s << endl;
}

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: TIME LIMIT EXCEEDED

Test 9

Group: 2

Verdict: TIME LIMIT EXCEEDED

Test 10

Group: 2

Verdict: TIME LIMIT EXCEEDED

Test 11

Group: 2

Verdict: TIME LIMIT EXCEEDED

Test 12

Group: 2

Verdict: TIME LIMIT EXCEEDED

Test 13

Group: 2

Verdict: TIME LIMIT EXCEEDED

Test 14

Group: 2

Verdict: TIME LIMIT EXCEEDED