191. 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.

 

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