Prove safety Offer - surface 15. The number of questions in a binary (bit calculation)

1. Topic

Please implement a function, an integer input, the output binary number represents the number 1. For example, to 9 is expressed as a binary 1001, there is a 2 1. Thus, if the input 9, the function output 2.

示例 1：
输入：00000000000000000000000000001011
输出：3
解释：输入的二进制串 00000000000000000000000000001011 中，
共有三位为 '1'。

示例 2：
输入：00000000000000000000000010000000
输出：1
解释：输入的二进制串 00000000000000000000000010000000 中，
共有一位为 '1'。

示例 3：
输入：11111111111111111111111111111101
输出：31
解释：输入的二进制串 11111111111111111111111111111101 中，
共有 31 位为 '1'。

Source: stay button (LeetCode)
link: https: //leetcode-cn.com/problems/er-jin-zhi-zhong-1de-ge-shu-lcof
copyrighted by deduction from all networks. Commercial reprint please contact the authorized official, non-commercial reprint please indicate the source.

2. Problem Solving

• n&(n-1)The resulting number than the nbinary one less1

class Solution {
public:
    int hammingWeight(uint32_t n) {
        int count = 0;
        while(n)
        {
        	n = n&(n-1);
        	count++;
        }
        return count;
    }
};