Add Binary

Description

Given two binary strings, return their sum (also a binary string).

The input strings are both non-empty and contains only characters 1 or 0.

Example 1:

Input: a = "11", b = "1"
Output: "100"

Example 2:

Input: a = "1010", b = "1011"
Output: "10101"

 

Constraints:

• Each string consists only of '0' or '1' characters.
• 1 <= a.length, b.length <= 10^4
• Each string is either "0" or doesn't contain any leading zero.

Solution(javascript)

/**
 * @param {string} a
 * @param {string} b
 * @return {string}
 */
const addBinary = function (a, b) {
  const reverse = x => x.split('').reverse()
  const { shorter, longer } = a.length > b.length
    ? { shorter: reverse(b), longer: reverse(a) }
    : { shorter: reverse(a), longer: reverse(b) }

  let reminder = 0
  const digits = longer.map((num1, index) => {
    let res = parseInt(num1, 10) + reminder
      + (parseInt(shorter[index], 10) ? parseInt(shorter[index], 10) : 0)
    if (res >= 2) {
      res -= 2
      reminder = 1
    } else {
      reminder = 0
    }
    return res
  })
  if (reminder === 1) {
    digits.push(reminder)
  }
  return digits.reverse().join('')
}