[LeetCode]191. Number of 1 Bits

题目描述：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.
分析：将一个无符号整数用二进制表示，并且返回其中的位数为1的个数（位操作）

解题思路:将n&n-1可以将最右边的1变为0。直到n为0，则可以计算n的二进制表示中1的个数。

public static int hammingWeight(int n) {        int count = 0;        while(n!=0){            count++;            n=n&(n-1);        }        return count;    }