[LeetCode] 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.

1、思路：

2、复杂度：

3、代码：

public class Solution {
    // you need to treat n as an unsigned value
    public int hammingWeight(int n) {
        int cnt=0,i=1;
        while(i<=32)
        {
            if((n&1)==1) cnt++;
            n=n>>1;
            i++;
        }
        return cnt;
    }
}

4、优化：

5、扩展：