[leetcode] 191. Number of 1 Bits 解题报告

题目链接: https://leetcode.com/problems/number-of-1-bits/
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: 按位与计算1的个数

代码如下:

class Solution {
public:
int hammingWeight(uint32_t n) {
unsigned int cnt = 0, num;
for(int i = 0; i< 32; i++)
{
num = 1<<i;
cnt += (num&n)?1:0;
}
return cnt;
}
};