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.

注意两点：1. 我用的 rightshift 是>>>, 是unsigned right shift

2. & 的优先级不如 ==， 所以要把&的两个参数括起来

 1 public class Solution {

 2     // you need to treat n as an unsigned value

 3     public int hammingWeight(int n) {

 4         int count = 0;

 5         for (int i=0; i<32; i++) {

 6             if ((n>>>i & 1) == 1) count++;

 7         }

 8         return count;

 9     }

10 }