coin_graph.py

def generate_stacks(n):
	if n == 1:
		yield (True,)
		yield (False,)
	else:
		for stack in generate_stacks(n - 1):
			yield stack + (True,)
			yield stack + (False,)

def stack_flip(stack, n):
	end = [not x for x in stack[0:n]]
	end.reverse()
	return stack[n:len(stack)] + tuple(end)

def stack_to_string(stack):
	def bool_to_str(x):
		return 'T' if x else 'H'

	return ''.join([bool_to_str(x) for x in stack])

def main():
	stack_size = 3

	results = {}

	for stack in generate_stacks(stack_size):
		for n in range(1, stack_size):
			inner_results = results.get(stack, [])
			inner_results.append((n, stack_flip(stack, n)))
			results[stack] = inner_results

	dot_file = ''
	for stack, inner_results in results.items():
		for n, inner_stack in inner_results:
			dot_file += '{} -> {} [label=\"{}\"];\n'.format(
				stack_to_string(stack), stack_to_string(inner_stack),
				n
			)

	with open('graph.dot', 'w') as f:
		f.write('digraph G {{\n{}}}'.format(dot_file))

if __name__ == '__main__':
	main()