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;
}
}