Countdown Solver Unfinished

countdownv1.py

import itertools

def _solve(target, numbers):
	#print 'Solving T=' + str(target) + ': ' + str(numbers)
	
	# base case
	if target in numbers:
		# solved.
		print target,
		return True	
	elif len(numbers) <= 1:
		# the target doesn't equal the number. Failed
		return False

	# use the first number of the list
	number = numbers[0]
	newNumbers = numbers[1:]
	
	# try 'minus'
	newTarget = target + number
	if _solve(newTarget, newNumbers):
		# solved, working backwards we want the inverse
		print number,
		print '-',
		return True

	# 'add'
	newTarget = target - number
	if _solve(newTarget, newNumbers):
		print number,
		print '+',
		return True

	if target % number == 0:
		# try product
		newTarget = target/number
		if _solve(newTarget, newNumbers):
			print number,
			print '*',
			return True

	newTarget = target*number
	if _solve(newTarget, newNumbers):
		print number,
		print '/',
		return True

def solve(target, numbers, solve_all=False):
	solved = False
	for n in xrange(len(numbers)):
		if solved and not solve_all:
			break

		for perm in itertools.permutations(numbers, n):
			if solved and not solve_all:
				break;

			if _solve(target, perm):
				print '=',
				print target
				solved = True