461. Hamming Distance

The Hamming distance between two integers is the number of positions at which the corresponding bits are different.

Given two integers x and y, calculate the Hamming distance.

Note: 0 ≤ x, y < 231.

Example:

Input: x = 1, y = 4

Output: 2

Explanation:
1   (0 0 0 1)
4   (0 1 0 0)
       ↑   ↑

The above arrows point to positions where the corresponding bits are different.

int hammingDistance(int x, int y) { // time: O(1); space: O(1)
    int res = 0, tmp = x ^ y;
    while (tmp) {
        if (tmp & 1) ++res;
        tmp >>= 1;
    }
    return res;
}

int hammingDistance(int x, int y) { // time: O(1); space: O(1)
    int res = 0, n = x ^ y;
    while (n) {
        ++res;
        n &= (n - 1);
    }
    return res;
}