LeetCode： Sort Array By Parity II

Question

Given an array A of non-negative integers, half of the integers in A are odd, and half of the integers are even.

Sort the array so that whenever A[i] is odd, i is odd; and whenever A[i] is even, i is even.

You may return any answer array that satisfies this condition.

Example 1:

Input: [4,2,5,7]

Output: [4,5,2,7]

Explanation: The outputs [4,7,2,5], [2,5,4,7], [2,7,4,5] would also have been accepted.

Solution

def sort_array_by_parity_ii(a)
  even_array = a.select{|element| element.even?}
  odd_array = a.select{|element| element.odd?}
  result = []
  i = 0

  while i < a.length/2
    result << even_array[i]
    result << odd_array[i]
    i += 1
  end
  result
end