题目描述
Write a function that takes an unsigned integer and returns the number of '1' bits it has (also known as the Hamming weight).
实例
Input: 11
Output: 3
Explanation: Integer 11 has binary representation 00000000000000000000000000001011
代码
public class Solution {
// you need to treat n as an unsigned value
public int hammingWeight(int n) {
int count=0;
while (n!=0)
{
n=n&(n-1);
count++;
}
return count;
}
}
分析
- 使用
n=n&(n-1);
可以将n的最后一个1变为0,循环直至n为0即可。 - 若使用移位操作会超时。
- 输入超过int的数时会报错“过大的整数”。