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.
很简单的一道位操作Bit Manipulation的题，最近新出的三道题都没有啥难度啊，这样会误导新人的，做了这三道得出个LeetCode没啥难度的结论，其实里面好题真的不少，难题也很多，经典题也多，反正就是赞赞赞，32个赞。
class Solution {
public:
int hammingWeight(uint32_t n) {
int res = ;
for (int i = ; i < ; ++i) {
res += (n & );
n = n >> ;
}
return res;
}
};