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.

題目標籤：Bit Manipulation

　　這題給我們一個integer，讓我們找到bits中1的個數，利用 & 1 判斷bit是不是1，然後利用 >> 來移動bits。

Java Solution:

Runtime beats 16.07%

完成日期：06/26/2017

關鍵詞：Bit Manipulation

關鍵點：用 & 拿到bit， 用 >> 來移動bits

 public class Solution

 {

     // you need to treat n as an unsigned value

     public int hammingWeight(int n)

     {

         int res = 0;

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

         {

             if((n & 1) == 1) // meaning the most right bit is 1

                 res++;

             n = n >> 1; // shift to right 1 bit

         }

         return res;

     }

 }

參考資料： N/A

LeetCode 演算法題目列表 - LeetCode Algorithms Questions List