[leetcode 191] Hamming weight

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.

Credits:
Special thanks to @ts for adding this problem and creating all test cases.

 

 1 int hammingWeight(uint32_t n) 
 2     {
 3         int count = 0;
 4 #if 0
 5         for (int i = 0; i < 32; i++)
 6             if (n & (1 << i))
 7                 count++;
 8 #else
 9         while (n)
10         {
11             count++;
12             n = n & (n - 1);
13         }
14 #endif
15         return count;
16     }