leetcode 191 Number of 1 Bits（难易度：Easy）

Number of 1 Bits

Write a function that takes an unsigned integer and returns the number of ’1' bits it has (also known as theHamming weight).

For example, the 32-bit integer ’11' has binary representation

00000000000000000000000000001011

, so the function should return 3.

代码：

解法一：

int hammingWeight(uint32_t n) {
int count = 0;
unsigned int flag = 1;
while (flag)
{
if(n & flag)
count ++;
flag = flag << 1;
}
return count;
}

解法二：

int hammingWeight(uint32_t n) {
int count = 0;
while (n)
{
++ count;
n = (n - 1) & n;
}
return count;
}原题地址：https://leetcode.com/problems/number-of-1-bits/