191. Number of 1 Bits

难度: Easy

题目描述

Given a positive integer n, write a function that returns the number of set bits 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

 

Follow up: If this function is called many times, how would you optimize it?

解题思路

代码实现

解决方案

java

class Solution {
    public int hammingWeight(int n) {
        
    }
}