Solves levels in the calculator game

the_calculator_game_solution.py

import re
print("Enter intial value:")
initial = int(input())
print("Enter goal:")
target = input()
print("Enter number of moves:")
moves = input()
print("Enter available buttons separated by commas (1, +1, -1, x2, /2, +/-, sum, 12=>34, reverse, <<, ^3, >, <, mirror)")
ops = map(str.strip,raw_input().split(','))
D = False
def sum_of_digits(x):
	sum = 0
	while x > 0:
		sum += x%10
		x /= 10
	return sum

def reverse(x):
	sum = 0
	while x > 0:
		sum *= 10
		sum += x%10
		x /= 10
	return sum

def shift_right(x):
	length = len(str(x))
	first_digit = x % 10
	x //= 10
	x += (10 ** (length-1) * first_digit)
	return x

def shift_left(x):
	length = len(str(x))
	exp = 10 ** (length-1)
	last_digit = x // exp 
	x %= exp
	x *= 10
	x += last_digit
	return x

def mirror(x):
	result = x
	while x > 0:
		result *= 10
		result += x % 10
		x //= 10
	return result


# For each operator string return an operation as lambda(a,b) and b where a is the original number.  
def parse_op(arg):
	operations = [  (r"^([0-9]+)$", lambda x,y: x * (10 ** len(str(y))) + y),
					(r"^\+([0-9]+)$", lambda x,y: x + y),
					(r"^-([0-9]+)$", lambda x,y: x - y),
					(r"^x([0-9]+)$", lambda x,y: x * y),
					(r"^/([0-9]+)$", lambda x,y: x / y),
					(r"^\+\/\-$", lambda x,y: -x),
					(r"^sum$", lambda x,y: sum_of_digits(x) ),
					(r"^([0-9]+)=>([0-9]+)$", lambda x,y: str(x).replace(str(y[0]),str(y[1]))),
					(r"^reverse$", lambda x,y: reverse(x) ),
					(r"^<<$", lambda x,y: x // 10 ),
					(r"^\^([0-9]+)$", lambda x,y: x ** y ),
					(r"^>$", lambda x,y: shift_right(x) ),
					(r"^<$", lambda x,y: shift_left(x) ),
					(r"^mirror$", lambda x,y: mirror(x) )]
	for op in operations:
		match = re.search(op[0],arg)
		if match:
			button = match.group(0)
			operation = op[1]
			if match.lastindex is 0 or match.lastindex is None:
				operand = 0
			elif match.lastindex is 1:
				operand = int(match.group(1))
			else:
				operand = (int(match.group(1)),int(match.group(2)))
			return operation,operand,button
	raise Exception("Could not parse operator")
	

def solve(initial, ops, target, moves_left, path):
	if initial == target:
		return path
	elif moves_left <= 0:
		return False
	else:
		for op in ops:
			operation = op[0]
			operand = op[1]
			button = op[2]
			result = int(operation(initial,operand))
			if D:
				print("result = "+str(result))
			full_path = solve(result,ops,target,moves_left-1,path + " " +button)
			if full_path:
				return full_path 
	return False

if D:
	op = parse_op(ops[0])
	x = op[0](initial,op[1])
	print(x)
else :
	operations = map(parse_op,ops)	
	print(solve(initial,operations, target, moves, ""))