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.

s思路：

1. 移位就可以了！

class Solution {
public:
int hammingWeight(uint32_t n) {
//
int res=0;
for(int i=0;i<32;i++){
if(n==0) break;//优化的不错：判断是否提前就等于0了，后面的操作就不必做了
res+=n&1;
n>>=1;
}
return res;
}
};