Sum of Digits in Base K

Given an integer n (in base 10) and a base k, return the sum of the digits of n after converting n from base 10 to base k.

After converting, each digit should be interpreted as a base 10 number and the sum should be returned in base 10.

Example 1:

Input: n = 34, k = 6
Output: 9
Explanation: 34 (base 10) expressed in base 6 is 54. 5 + 4 = 9.

Example 2:

Input: n = 10, k = 10
Output: 1
Explanation: n is already in base 10. 1 + 0 = 1.

Approach

C++

#include <bits/stdc++.h>
using namespace std;

string replaceDigits(string s)
{

    int n = s.size();
    string str = "";
    int i = 0;
    while (i < n)
    {
        str += s[i];
        i++;
        if (i < n)
            str += s[i - 1] + s[i] - '0';
        i++;
    }
    return str;
}

int main()
{
    string s = "a1c1e1";

    cout << replaceDigits(s) << "\n";

    return 0;
}