【leetcode】191. Number of 1 Bits

题目：
Write a function that takes an unsigned integer and return the number of ‘1’ bits it has (also known as the Hamming weight).

---

思路：
利用mask挨个比较每一位就好了。

---

代码实现：

class Solution {
public:
    int hammingWeight(uint32_t n) {
        uint32_t mask = 1;
        
        int count = 0;
        while (mask){
            if (n & mask){
                ++count;
            }
            
            mask <<= 1;
        }
        
        return count;
    }
};