191. Number of 1 Bits

Posted 2020-08-02 whl-hl

1. 问题描述

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

For example, the 32-bit integer ’11‘ has binary representation 00000000000000000000000000001011, so the function should return 3.

Tags: Bit Manipulation
Similar Problems: (E) Reverse Bits (E) Power of Two (M) Counting Bits

2. 解题思路

• 《剑指offer》

3. 代码

 1 class Solution {
 2 public:
 3     int hammingWeight(uint32_t n) 
 4     {
 5         int i = 0;
 6         while (0 != n)
 7         {
 8             uint32_t t = n-1;
 9             n = t & n;
10             i++;
11         }
12         return i;
13     }
14 };

4. 反思