🟢  Number of 1 Bits

<aside> 💡 AND (&) the whole number to get last bit. Then do UNSIGNED RIGHT SHIFT (>>>) and repeat until number ends (becomes zero).

</aside>

https://leetcode.com/problems/number-of-1-bits/

function hammingWeight(number) {
  let count = 0;

  function scan(current) {
    if (current == 0) {
      return;
    }
    if (current & 1 == 1) {
      count++;
    }
    return scan(current >>> 1);
  }

  scan(number);

  return count;
}

• Alternative solution

🟡 Counting Bits

<aside> 💡 Do “Number of 1 bits” for every number in a range.

</aside>

https://leetcode.com/problems/counting-bits/

function countBits(number) {
  const result = [];

  function getCount(number, count = 0) {
    if (number === 0) {
      return count;
    }
    if (current & 1 ===1) {
      count++; 
    }
    return getCount(number >>> 1, count);
  }

  for (let i = 0; i <= number; i++) {
    result.push(getCount(i));
  }

  return result;
}

• Solution

🟡 Sum of Two Integers