Recursive function output

Question

#include <stdio.h>

int mystery(int n) {
    if (n == 0) {
        return 0;
    } else if (n % 2 == 0) {
        return mystery(n / 2);
    } else {
        return 1 + mystery(n / 2);
    }
}

int main() {
    int result = mystery(13);
    printf("%d\n", result);
    return 0;
}

What will be the output of the program?

Answer 1

Output will be 3.

In the first iteration n= 13 so return 1+ f(13/6)

In the 2nd iteration n = 6 so return f(3)

In the 3rd iteration n= 3 so return 1 + f(3/2)

In the 4th iteration n = 2 so return f(2/1)

In the 5th iteration n= 1 so return 1+ f(1/2)

In the 6th iteration n=0 so return 0

Hence finally return = 1 + 1+1 = 3

So, result= 3

So , 3 will be output of the program.

Answer 2

mystery(13) → 13 is ODD  → 1 + mystery(6)
mystery(6)  → 6  is EVEN →     mystery(3)
mystery(3)  → 3  is ODD  → 1 + mystery(1)
mystery(1)  → 1  is ODD  → 1 + mystery(0)
mystery(0)  → BASE CASE  → 0

ans 3