写一个贪吃蛇的代码

```python import sys import random import pygame from pygame.locals import * pygame.init() FPS = 10 WINDOW_WIDTH = 640 WINDOW_HEIGHT = 480 CELL_SIZE = 20 CELL_WIDTH = int(WINDOW_WIDTH / CELL_SIZE) CELL_HEIGHT = int(WINDOW_HEIGHT / CELL_SIZE) WHITE = (255, 255, 255) BLACK = (0, 0, 0) RED = (255, 0, 0) GREEN = (0, 255, 0) def main(): global FPSCLOCK, DISPLAYSURF, BASICFONT FPSCLOCK = pygame.time.Clock() DISPLAYSURF = pygame.display.set_mode((WINDOW_WIDTH, WINDOW_HEIGHT)) BASICFONT = pygame.font.Font('freesansbold.ttf', 18) pygame.display.set_caption('贪吃蛇') while True: run_game() show_gameover_screen() def run_game(): start_x = random.randint(5, CELL_WIDTH - 6) start_y = random.randint(5, CELL_HEIGHT - 6) worm_coords = [{'x': start_x, 'y': start_y}, {'x': start_x - 1, 'y': start_y}, {'x': start_x - 2, 'y': start_y}] direction = RIGHT apple = get_random_location() while True: for event in pygame.event.get(): if event.type == QUIT: terminate() elif event.type == KEYDOWN: if (event.key == K_LEFT or event.key == K_a) and direction != RIGHT: direction = LEFT elif (event.key == K_RIGHT or event.key == K_d) and direction != LEFT: direction = RIGHT elif (event.key == K_UP or event.key == K_w) and direction != DOWN: direction = UP elif (event.key == K_DOWN or event.key == K_s) and direction != UP: direction = DOWN elif event.key == K_ESCAPE: terminate() if worm_coords[HEAD]['x'] == -1 or worm_coords[HEAD]['x'] == CELL_WIDTH or worm_coords[HEAD]['y'] == -1 or worm_coords[HEAD]['y'] == CELL_HEIGHT: return for worm_body in worm_coords[1:]: if worm_body['x'] == worm_coords[HEAD]['x'] and worm_body['y'] == worm_coords[HEAD]['y']: return if worm_coords[HEAD]['x'] == apple['x'] and worm_coords[HEAD]['y'] == apple['y']: apple = get_random_location() else: del worm_coords[-1] if direction == UP: new_head = {'x': worm_coords[HEAD]['x'], 'y': worm_coords[HEAD]['y'] - 1} elif direction == DOWN: new_head = {'x': worm_coords[HEAD]['x'], 'y': worm_coords[HEAD]['y'] + 1} elif direction == LEFT: new_head = {'x': worm_coords[HEAD]['x'] - 1, 'y': worm_coords[HEAD]['y']} elif direction == RIGHT: new_head = {'x': worm_coords[HEAD]['x'] + 1, 'y': worm_coords[HEAD]['y']} worm_coords.insert(0, new_head) DISPLAYSURF.fill(BLACK) draw_grid() draw_worm(worm_coords) draw_apple(apple) draw_score(len(worm_coords) - 3) pygame.display.update() FPSCLOCK.tick(FPS) def draw_press_key_msg(): press_key_surf = BASICFONT.render('按任意键继续...', True, WHITE) press_key_rect = press_key_surf.get_rect() press_key_rect.topleft = (WINDOW_WIDTH - 200, WINDOW_HEIGHT - 30) DISPLAYSURF.blit(press_key_surf, press_key_rect) def check_for_key_press(): if len(pygame.event.get(QUIT)) > 0: terminate() key_up_events = pygame.event.get(KEYUP) if len(key_up_events) == 0: return None if key_up_events[0].key == K_ESCAPE: terminate() return key_up_events[0].key def show_gameover_screen(): gameover_surf = BASICFONT.render('游戏结束', True, WHITE) gameover_rect = gameover_surf.get_rect() gameover_rect.midtop = (WINDOW_WIDTH / 2, 10) DISPLAYSURF.blit(gameover_surf, gameover_rect) draw_press_key_msg() pygame.display.update() pygame.time.wait(500) check_for_key_press() while True: if check_for_key_press(): pygame.event.get() return def terminate(): pygame.quit() sys.exit() def get_random_location(): return {'x': random.randint(0, CELL_WIDTH - 1), 'y': random.randint(0, CELL_HEIGHT - 1)} def draw_score(score): score_surf = BASICFONT.render('得分： %s' % (score), True, WHITE) score_rect = score_surf.get_rect() score_rect.topleft = (WINDOW_WIDTH - 120, 10) DISPLAYSURF.blit(score_surf, score_rect) def draw_worm(worm_coords): for coord in worm_coords: x = coord['x'] * CELL_SIZE y = coord['y'] * CELL_SIZE worm_segment_rect = pygame.Rect(x, y, CELL_SIZE, CELL_SIZE) pygame.draw.rect(DISPLAYSURF, GREEN, worm_segment_rect) worm_inner_segment_rect = pygame.Rect(x + 4, y + 4, CELL_SIZE - 8, CELL_SIZE - 8) pygame.draw.rect(DISPLAYSURF, GREEN, worm_inner_segment_rect) def draw_apple(coord): x = coord['x'] * CELL_SIZE y = coord['y'] * CELL_SIZE apple_rect = pygame.Rect(x, y, CELL_SIZE, CELL_SIZE) pygame.draw.rect(DISPLAYSURF, RED, apple_rect) def draw_grid(): for x in range(0, WINDOW_WIDTH, CELL_SIZE): pygame.draw.line(DISPLAYSURF, WHITE, (x, 0), (x, WINDOW_HEIGHT)) for y in range(0, WINDOW_HEIGHT, CELL_SIZE): pygame.draw.line(DISPLAYSURF, WHITE, (0, y), (WINDOW_WIDTH, y)) if __name__ == '__main__': main() ```