leetcode 191

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.

求出输入整数的32位中有多少位值为1.

代码如下：

 

class Solution {
public:
    int hammingWeight(uint32_t n) {
        unsigned pos = 1 << 31;
        int count = 0;
        while(pos)
        {
            if(pos & n)
            {
                count++;
            }
            pos >>= 1;
        }
        return count;
    }
};