LeetCode： Plus One

Question

Given a non-empty array of decimal digits representing a non-negative integer, increment one to the integer.

The digits are stored such that the most significant digit is at the head of the list, and each element in the array contains a single digit.

You may assume the integer does not contain any leading zero, except the number 0 itself.

Example 1:

Input: digits = [1,2,3]

Output: [1,2,4]

Explanation: The array represents the integer 123.

Example 2:

Input: digits = [4,3,2,1]

Output: [4,3,2,2]

Explanation: The array represents the integer 4321.

Example 3:

Input: digits = [0]

Output: [1]

Solution #1

def plus_one(digits)
  result = (digits.join.to_i + 1)
  if result == 1
    digits.pop
    digits.push(1)
  else
    result.to_s.split('').map { |element| element.to_i }
  end
end

Solution #2

def plus_one(digits)
  result = (digits.join.to_i + 1).digits.reverse
  if result == [1]
    digits.pop
    digits.push(1)
  else
    result
  end
end