LeetCode-Number of 1 Bits

文章目录

LeetCode地址：https://leetcode.com/problems/number-of-1-bits/

Problem:
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

• 使用移位操作，每次将最后的最低位累加
• 我想说一模一样的代码，Java和C++的执行效率真的相差挺大

class Solution {
public:
    int hammingWeight(uint32_t n) {
        int i=0;
        int sum=0;
        for(;i<32;i++)
        {
            
            sum+=n&0x1;
            n=n>>1;
        }
        
        return sum;
    }
};

the Runetime is 10ms

public class Solution {
    // you need to treat n as an unsigned value
    public int hammingWeight(int n) {
        int i=0;
        int sum=0;
        for(;i<32;i++)
        {
            
            sum+=n&0x1;
            n=n>>1;
        }
        
        return sum;
    }
}

the Runtime is 239ms

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