[勇者闯LeetCode] 191. Number of 1 Bits

[勇者闯LeetCode] 191. Number of 1 Bits

Description

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.

Information

Tags: Bit Manipulation

Difficulty: Easy

Solution

利用

n-1

与

n

进行“与”操作，消去

n

的二进制表示的最后一个1，直到

n

等于0。

C++ Code

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