Question:

We have two special characters. The first character can be represented by one bit 0. The second character can be represented by two bits (10 or 11).

Now given a string represented by several bits. Return whether the last character must be a one-bit character or not. The given string will always end with a zero.

Example:

  1. Input: 
  2. bits = [1, 0, 0]
  3. Output: True
  4. Explanation: 
  5. The only way to decode it is two-bit character and one-bit character.
  6.  So the last character is one-bit character.
  9. Input: 
  10. bits = [1, 1, 1, 0]
  11. Output: False
  12. Explanation: 
  13. The only way to decode it is two-bit character and two-bit character. 
  14. So the last character is NOT one-bit character.

Solution:

/**
 * @param {number[]} bits
 * @return {boolean}
 */
var isOneBitCharacter = function(bits) {
  let ones = 0;

  for (let i = bits.length - 2; i >= 0 && bits[i] !== 0; i--) {
    ones++;
  }

  if (ones % 2 > 0) return false;
  return true;
};