Question: Write a function that takes an unsigned integer and returns the number of '1' bits it has (also known as the Hamming weight).
Example 1:
Input: n = 00000000000000000000000000001011
Output: 3
Explanation: The input binary string 00000000000000000000000000001011 has a total of three '1' bits.
My Code
var hammingWeight = function(n) {
for (i=0; i<32; i++) {
var mask = 1;
var count = 0;
if ((mask & n) != 0 ) {
mask <<= 1;
count++;
}
return count;
}
};
Test Case:
00000000000000000000000000001011
00000000000000000000000010000000
11111111111111111111111111111101
Expected Output:
3
1
31
Output:
1
0
1
What did I do wrong with my code?
You have a few issues here:
count and mask inside of your for loop.returning after the first iteration of the loop, instead of waiting for the whole thing to count up.mask if a bit is 1.Here is a corrected function:
var hammingWeight = function(n) {
var count = 0;
var mask = 1;
for (i=0; i<32; i++) {
if ((mask & n) != 0 ) {
count++;
}
mask <<= 1;
}
return count;
};
A shorter way to write this could be:
const hammingWeight = value => [...value].filter(f => f == 1).length;
Explanation:
[...value] this will create an array of 0's and 1's based on your string
.filter(f => f == 1) will filter the array, keeping only the 1 values
.length gives you the length of the filtered array