LeetCode 191. Number of 1 bits （位1的数量）

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.

 

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题目标签：Bit Manipulation

　　这题给我们一个integer，让我们找到bits中1的个数，利用 & 1 判断bit是不是1，然后利用 >> 来移动bits。

 

Java Solution:

Runtime beats 16.07% 

完成日期：06/26/2017

关键词：Bit Manipulation

关键点：用 & 拿到bit， 用 >> 来移动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;
    }
}

参考资料： N/A

 

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