Snake game question :

input

2 3
4
0 1
0 2
1 2
1 1
8
R
R
D
L
U
R
D
L

snake.py

import sys


class Snake :
	def __init__(self, x, y, d) :
		self.x = x
		self.y = y
		self.dir = d  # U D L R


def move_by_direction( x, y, d, new_snake =  False ) :
	if d == 'U' :
		if new_snake is False :
			y = y - 1
		else :
			y = y+1
	elif d == 'D' :
		if new_snake is False :
			y = y + 1
		else :
			y = y - 1
	elif d == 'R' :
		if new_snake is False :
			x = x + 1
		else:
			x = x - 1
	elif d == 'L' :
		if new_snake is False :
			x = x - 1
		else:
			x = x + 1
	# print x,y,d
	return x,y


def check_for_food(foods, x, y) :
	for (fx,fy) in foods :
		# print fx,fy, x, y
		if fx == x and fy == y :
			return True

	return False


def snake_move( foods, moves ) :
	snake = []
	for count,move in enumerate(moves) :
		if not snake :
			snake.append( Snake(0, 0, move)) # initialise the snake object

		# print snake[0].x,snake[0].y, snake[0].dir 
		
		#regular movement
		#updating the directions from the previous one and moving
		for i in reversed(xrange( len(snake))) :
			if i == 0 :
				snake[i].dir = move
			else :
				snake[i].dir = snake[i-1].dir

			x = snake[i].x
			y= snake[i].y
			snake[i].x,snake[i].y = move_by_direction(x,y,snake[i].dir)

		if check_for_food(foods, snake[0].x, snake[0].y) is True :
			last_dir = snake[-1].dir
			x = snake[-1].x
			y= snake[-1].y
			x,y = move_by_direction(x,y,last_dir, new_snake= True)
			new_snake=  Snake( x, y, last_dir)  #adding new snake
			snake.append(new_snake)

		if (len(snake) > 1) :
			for s in xrange(1, len(snake)) :
				if snake[0].x == snake[s].x and snake[0].y == snake[s].y :  #snake bites itself
					return (count+1)

	return -1  #snake never bites itself



if __name__ == '__main__' :
	lines = sys.stdin.readlines()

	food_count = int(lines[1])
	foods = []
	for i in xrange(food_count) :
		y,x = lines[2 + i].split(' ')
		foods.append( (int(x),int(y) ) )

	move_count = int( lines[2 + food_count] )
	moves = []

	for i in xrange( move_count ) :
		move = lines[3 + food_count + i]
		moves.append(move.strip())

	print snake_move(foods, moves) 

The first line will be the size of the sandbox R C in rows & columns separated by a space, where 1 < R ≤
100 and 1 < C ≤ 100. The next line will be the total number of food locations, 2 < M ≤ 400, followed by
that many lines of R i C i (coordinates here are zero-indexed). The next line will be the total number of
moves 3< N ≤ 600, followed by that many lines each having a single-character directional code. The
codes are:
U : Up (row-1)
R : Right (col+1)
L : Left (col-1)
D : Down (row+1)
Note that the directions provided will never cause the snake to go beyond the bounds of the sandbox.