191. Number of 1 Bits

题目

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.

Credits: Special thanks to @ts for adding this problem and creating all test cases.

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思路

n&(n-1)会把n最后的一个bit为1的改成0，循环遍历计算bit 1的个数

代码