Towers of Hanoi using Stack (stack, recursion)

towers_of_hanoi_with_stack.rb

# We have a pole with a certain number of disks staked on it; 
# call this the source pole. We want move all of these to the
# destination pole, using a third (auxiliary) pole as an
# intermediate resting place. The catch is that you can move
# only one disk at the time, and you cannot ever place a larger
# disk onto a smaller one.

def towers(list)
  while !list.empty?
    n, src, dst, aux = list.pop
    if n == 1
      puts "Move disk from #{src} to #{dst}"
    else
      list.push [n-1, aux, dst, src]
      list.push [1, src, dst, aux]
      list.push [n-1, src, aux, dst]
    end
  end
end

list = []
list.push([3, "a", "c", "b"])

towers(list)