### Question

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.

### Analysis

In order to remove the last ‘1’ bit, we use this operation:

```
n = n & (n - 1);
```

### Solution

Just remove all the ‘1’ bits.

### Code

```
public class Solution {
public int hammingWeight(int n) {
int count = 0;
while (n != 0) {
n = n & (n - 1);
count++;
}
return count;
}
}
```