look and tell

#include <iostream>
#include <vector>
#include <string>
using namespace std;
int main()
{
    int k, i, j, num;
    string S, T;
    cin >> k;
    S = '1';
    for (int num = 0; num < k-1; num++) {
        T = "";
        i = 0;
        while (i < S.size()) {
            j = 1;
            while (i+1 < S.size() && (S[i + 1]==S[i])) {
                j++;
                i++;
            }
            T += to_string(j) + S[i];
            i++;
        }
        S = T;
    }
    cout << S;
    return 0;
}