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.
class Solution { public: int hammingWeight(uint32_t n) { int num; for(num = 0;n;num++) { n &= n-1;//n和n-1相与，就去掉了二进制中的最右边一个1 } return num; } };
参考338题
leetcode 191. Number of 1 Bits
原文：http://www.cnblogs.com/dystopia/p/5312257.html