A lesson in recursion

tower_of_hanoi.rb

# LETS GET READY TO RECURSE!!!!!!
#
# Tower of Hanoi
#
# You have 4 discs which vary in size from small to large
# There are 3 pegs, A, B, C, respectively
#
# The discs are all currently on peg A, with the largest disc on the bottom,
# and the smallest disc on the top.
#
#
# |      - 1 -     |                 |                 |
# |     -- 2 --    |                 |                 |
# |    --- 3 ---   |                 |                 |
# |   ---- 4 ----  |                 |                 |
# _________A________________B_________________C_________
#
#
# Get the discs from peg A to peg C.
#
# Rules:
# - Only one disk may be moved at a time.
# - Each move consists of taking the upper disk from one of the pegs and sliding
#   it onto another peg, on top of the other disks that may already be present on that peg.
# - No disk may be placed on top of a smaller disk (can't put disc 4 on top of disc 1).
#
# One method for setting this up might look like:
#
# a = [1,2,3,4]
# b = [] # empty Array
# c = [] # empty Array
#
# Then, as you move items(discs) between Arrays(pegs), you can't ever allow
# a larger number occurs before a smaller one in any Array, like:
#
# c = [2,1] # WRONG!
#
# Write a method that will call itself recursively until the discs are stacked on the C peg
# with the largest (4) on the bottom and the smallest (1) on top. So, write that method so
# that in the end the numbers are in the same order but in Array c.
#

a = [1,2,3,4]
b = []
c = []

# Move the disks from one peg to another following the rules of Hanoi.
#
# number_of_disks - the total number of disks
# from - the starting peg
# to - the ending (goal) peg
# via - the remaining peg (b in this case)
#
def move_disk(number_of_disks,from,to,via)
  # Do your magic here
  # your method should return to
  to
end

# here we go!
puts move_disk(4, a, c, b)