Sum of two numbers with bitwise operator

Question

I am pasting the code to find the sum of two numbers with bitwise operator. Please suggest if it can be optimized. Thanks...

public static int getSum(int p, int          


        

Answer 1

Think in entire bits:

public static int getSum(int p, int q)
{
    int result = p ^ q; // + without carry 0+0=0, 0+1=1+0=1, 1+1=0
    int carry = (p & q) << 1; // 1+1=2
    if (carry != 0) {
        return getSum(result, carry);
    }
    return result;
}

This recursion ends, as the carry has consecutively more bits 0 at the right (at most 32 iterations).

One can easily write it as a loop with p = result; q = carry;.

Another feature in algorithmic exploration is not going too far in differentiating cases. Above you could also take the condition: if ((result & carry) != 0).