191. Number of 1 Bits

難度: Easy

類型: Divide and Conquer,Bit Manipulation 

CPP程式下載: 191.cpp

Topic:

Given a positive integer n, write a function that returns the number of  in its binary representation (also known as the Hamming weight).

 

Example 1:

Input: n = 11

Output: 3

Explanation:

The input binary string 1011 has a total of three set bits.

Example 2:

Input: n = 128

Output: 1

Explanation:

The input binary string 10000000 has a total of one set bit.

Example 3:

Input: n = 2147483645

Output: 30

Explanation:

The input binary string 1111111111111111111111111111101 has a total of thirty set bits.

 

Constraints:

• 1 <= n <= 231 - 1

Consideration:

Bit calculation, bit operation till n becomes 0.

Code:

class Solution {

public:

    int hammingWeight(int n) {

        int out_num=0;

        while (n)

        {

            if (n & 1) out_num++;

            n>>=1;

        }

        return out_num; 

    }

};

Result:

https://leetcode.com/problems/number-of-1-bits/submissions/1941832985/

Accepted

598 / 598 testcases passed

tendchen

submitted at Mar 08, 2026 18:09

Runtime

0ms

Beats100.00%

Memory

8.22MB

Beats47.99%

Code