Question

Assume that the method enigma has been defined as follows:

public int enigma(int n)
{
    int m;

    while (n >= 10) {
        m = 0;
        while (n > 10) {
            m += n % 10;
            n /= 10;
        }
        n = m;
    }
    return (n);
}

What is the value of enigma(1995) ?
I understood that the value of enigma(1995) is 3. What is the step by step?

Answer 1

The outer while runs until n becomes less than 10.

The inner loop runs until n becomes less than or equal to 10, then we assign the value of m to n, so the outer loop can be evaluated again.

What happens in the inner loop? m is incremented by the remainder of n divided by 10 (so 5 when n==1995), then n is set to be the (integer) result of the division (so now n==199). This is repeated a few times:

n=1995 => m=5,n=f199
n=199  => m=5+9=14,n=19
n=19   => m=14+9=23,n=1

Since n is now not larger than 10, the inner loop ends and n is set to m(==23), then we do this again:

n=23 => m=3,n=2

Since n is now not larger than 10, the inner loop ends and n is set to m(==3). Since now n is less than 10, the outer loop exist and we arrived to the result of n(==3).