191. Number of 1 Bits

Return the number of set bits (1s) in the binary representation of the positive integer n.

n & (n − 1) clears the lowest set bit. Count how many times you can do that before n becomes 0.

1function hammingWeight(n: number): number {
2  let count = 0;
3  while (n !== 0) {
4    n &= n - 1;
5    count++;
6  }
7  return count;
8}