Digital Root

 4. Digital Root 

Easy Accuracy: 53.0% Submissions: 13170 Points: 2

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You are given a number n. You need to find the digital root of n. DigitalRoot of a number is the recursive sum of its digits until we get a single digit number.

Example 1:

Input:
n = 1
Output:  1
Explanation: Digital root of 1 is 1

Example 2:

Input:
n = 99999
Output: 9
Explanation: Sum of digits of 99999 is 45
which is not a single digit number, hence
sum of digit of 45 is 9 which is a single
digit number.

Your Task:
You don't need to read input or print anything. Your task is to complete the function digitalRoot that takes n as parameter and returns the digital root of n. 

Expected Time Complexity: O((Num of Digits)2).
Expected Auxiliary Space: O(Num of Digits).

Constraints:
1 <= n <= 107

// Online C++ compiler to run C++ program online

#include <iostream>

using namespace std;

int sum(int n){

        int sum=0;

        while(n!=0){

            sum+=n%10;

            n=n/10;

        }

        return sum;

    }

int main() {

    // Write C++ code here

    int n;

    cin>>n;

    while(n>9){

        n=sum(n);

        

    }

    cout<<n;

    

    return 0;

}