461. Hamming Distance

• Difficulty: Easy

TheHamming distancebetween two integers is the number of positions at which the corresponding bits are different.

Given two integersxandy, 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.

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思路：记住一个数&1就是清零其他位，只保留最后一位。所以每次都比较x&1和y&1，如果不相等就cnt加1，记住每次比较完两个数都要向后移一位。

class Solution(object):
    def hammingDistance(self, x, y):
        """
        :type x: int
        :type y: int
        :rtype: int
        """
        cnt = 0
        while x or y:
            if x & 1 != y & 1:
                cnt += 1
            x >>= 1
            y >>= 1
        return cnt