diff --git a/snake.py b/snake.py
index 537316e..4af5c14 100644
--- a/snake.py
+++ b/snake.py
@@ -1,6 +1,6 @@
 import pygame
 from pygame import locals
-
+import random
 # 初始化pygame，为使用硬件做准备
 pygame.init()
 
@@ -23,6 +23,9 @@ position = [(180, 90), (180, 120), (210, 120), (x, y)]
 setheading = "right"
 snake_head = right
 
+apple_x = 360
+apple_y = 300
+
 while True:
     for event in pygame.event.get():
         if event.type == locals.QUIT:
@@ -51,8 +54,19 @@ while True:
         y -= 30
     else:
         y += 30
+    if (x,y) in position:
+        exit()
     position.append((x, y))
-    position.pop(0)
+    if x==apple_x and y==apple_y:
+        num1 = random.randint(1,22)
+        num2 = random.randint(1,16)
+        apple_x = num1*30-30
+        apple_y = num2*30-30
+    else:
+        position.pop(0)
+    if x<0 or x>630 or y<0 or y>450:
+        exit()
+    
     # 将背景图画上去
     screen.blit(background, (0, 0))
     # 将贪吃蛇的头画上去
@@ -62,7 +76,7 @@ while True:
         screen.blit(body, position[i])
 
     # 将果实画上去
-    screen.blit(food, (360, 300))
+    screen.blit(food, (apple_x,apple_y))
     # 刷新画面
     pygame.display.update()
     FPSCLOCK.tick(3)
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