Leetcode 191. Number of 1 Bits

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.
Analysis:

This question is quite simple, you can just count the number of one bit using >>

or you can use n = n & (n - 1) to turn the last bit which is 1 to 0;

code:

public class Solution {

public int hammingWeight(int n) {
int result = 0;
for(int i = 0; i < 32; i++){
if((n & 1) == 1)
result++;
n = n >> 1;
}
return result;
}
}

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