Q191 Number of 1 Bits

Write a function that takes an unsigned integer and returns the number of ’1' bits it has (also known as the Hamming weight).

For example, the 32-bit integer ’11' has binary representation 00000000000000000000000000001011, so the function should return 3.

解题思路：

此题为计算海明距离。先将整数转化为二进制，然后将数字1 存入列表，对列表求和。

Python实现：

class Solution(object):
    def hammingWeight(self, n):
        """
        :type n: int
        :rtype: int
        """
        return sum([int(x) for x in bin(n)[2:] if x == '1'])

a = 11
b = Solution()
print(b.hammingWeight(a))  # 3  # '1011'