Hamming Distance

hammingDistance.js

/**
 * @param {number} x
 * @param {number} y
 * @return {number}
 */
var hammingDistance = function(x, y) {
    let xor = x ^ y;
    let count = 0;
    while (xor != 0) {
        xor &= xor - 1;
        count++;
    }

    return count;
};

// xor operation returns returns 0 if both bits are same and 1 otherwise
// x xor y will give return 1 where bits differ, so we have to count all the set bits in x xor y
// x & (x-1) changes the least significant set bit of a number, we do this till we get 0
// increase count everytime we do (x & (x-1)) which is in this case (xor & (xor -1))
// return count

// Time: O(1)
// Space: O(1)