[LeetCode] Number of 1 Bits

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：

对于正整数，n=n&(n-1)表示去除最后一个1。如此计数。下面是代码：

class Solution {
public:
    int hammingWeight(uint32_t n) {
        int result=0;
        while(n!=0){
            n=n&(n-1);      //这个式子表示去掉n最后一个1
            result++;
        }
        return result;
    }
};

原文：http://blog.csdn.net/kangrydotnet/article/details/44920031