import math
import random

class Array:
  def __init__(self, n):
    """
    Parameters
    ----------
    n : int
      The size of the array
    """
    self.array = random.sample(range(n), n)

  def reverse(self):
    """Rearranges an array backwards

    Raises
    ------
    Exception
      If the input array is empty
    """
    if self.array:
      print('\n')
      print(self.array)
      print('\n')
      # Traverses half of the array
      for i in range(math.floor(len(self.array) / 2)):
        # Moves the last element to the first place and the first element to the last place
        self.array[i], self.array[len(self.array) - i - 1] = self.array[len(self.array) - i - 1], self.array[i]
      print(self.array)
      print('\n')
    else:
      raise Exception('Empty array!')