[LeetCode]191.Number of 1 Bits

2024-02-19 01:08

文章标签 leetcode number 191 bits

本文主要是介绍[LeetCode]191.Number of 1 Bits，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

题目

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

每次左移一位，进行&运算。

代码

/*------------------------------------------------------
*   日期：2014-04-12
*   作者：SJF0115
*   题目: 191.Number of 1 Bits
*   网址：https://leetcode.com/problems/number-of-1-bits/
*   结果：AC
*   来源：LeetCode
*   博客：
--------------------------------------------------------*/
#include <iostream>
#include <vector>
using namespace std;class Solution {
public:int hammingWeight(uint32_t n) {if(n == 0){return 0;}//ifif(n == 1){return 1;}//ifint count = 0;for(int i = 0;i < 32;++i){if((n&(1<<i)) > 0){++count;}//if}//forreturn count;}
};int main(){Solution solution;uint32_t num = 1;cout<<""<<solution.hammingWeight(num)<<endl;return 0;
}

思路二

每执行一次x = x&(x-1)，会将x用二进制表示时最右边的一个1变为0，因为x-1将会将该位(x用二进制表示时最右边的一个1)变为0。

代码二

/*------------------------------------------------------
*   日期：2014-04-12
*   作者：SJF0115
*   题目: 191.Number of 1 Bits
*   网址：https://leetcode.com/problems/number-of-1-bits/
*   结果：AC
*   来源：LeetCode
*   博客：
--------------------------------------------------------*/
#include <iostream>
#include <vector>
using namespace std;class Solution {
public:int hammingWeight(int n) {int count = 0;while(n != 0){n = n & (n-1);count++;}//whilereturn count;}
};int main(){Solution solution;uint32_t num = 11;cout<<""<<solution.hammingWeight(num)<<endl;return 0;
}