[LeetCode] 191. 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.

思路：n和(n-1)按位与可以去掉二进制相对最右边一位1

          经过count次n&(n-1)直到n变为0，count就是n的二进制中表示1的个数

public class Solution {

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