Maximum of sum and product of digits until number is reduced to a single digit in C++

In this tutorial, we will be discussing a program to find maximum of sum and product of digits until number is reduced to a single digit

For this we will be provided with a random number. Our task is to find and print out the maximum of sum and product of the digits of the given number until it coverts to a single digit

Example

#include<bits/stdc++.h>
using namespace std;
//converting number to single digit by adding
long repeatedSum(long n) {
   if (n == 0)
      return 0;
   return (n % 9 == 0) ? 9 : (n % 9);
}
//converting number to single digit by multiplying
long repeatedProduct(long n) {
   long prod = 1;
   while (n > 0 || prod > 9) {
      if (n == 0) {
         n = prod;
         prod = 1;
      }
      prod *= n % 10;
      n /= 10;
   }
   return prod;
}
//finding maximum
long maxSumProduct(long N) {
   if (N < 10)
      return N;
   return max(repeatedSum(N), repeatedProduct(N));
}
int main() {
   long n = 631;
   cout << maxSumProduct(n)<<endl;
   return 0;
}

Output

8