LeetCode Number of 1 Bits

1.题目

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.

2.解决方案1

class Solution {
public:
    int hammingWeight(uint32_t n) {
        int count = 0;

    while (n)
    {
        ++ count;
        n = (n - 1) & n;
    }

    return count;
    }
};

比如容易想到的解决方案是下面这个，每次往右移动一位，判断最后一位是不是1，但这样会有点慢，32位就要移动32次。上面的方法巧妙的