binary search

binary_search.rb

def binary_search(num, array)

  return -1 if !array.include?(num)

  index = (array.length)/2

  index_array = [(array.length), 0]

  until num == array[index]
    index = (index_array[0] + index_array[1])/2
    num > array[index] ? index_array[1] = index : index_array[0] = index
  end

   index
end