[LeetCode] 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.

思路：n和(n-1)按位與可以去掉二進制相對最右邊一位1

          經過count次n&(n-1)直到n變爲0，count就是n的二進制中表示1的個數

public class Solution {
    
    public int hammingWeight(int n) {
        int count=0;
        while(n!=0){
            count++;
            n=n&(n-1);
        }
        return count;
    }
}