自学教程：Python实现自动玩贪吃蛇程序

pip install pygame

import pygame,sys,time,randomfrom pygame.locals import *

redColour = pygame.Color(255,0,0)blackColour = pygame.Color(0,0,0)whiteColour = pygame.Color(255,255,255)greenColour = pygame.Color(0,255,0)headColour = pygame.Color(0,119,255)

IGHT = 15WIDTH = 15FIELD_SIZE = HEIGHT * WIDTH# 蛇头位于snake数组的第一个元素HEAD = 0

FOOD = 0UNDEFINED = (HEIGHT + 1) * (WIDTH + 1)SNAKE = 2 * UNDEFINED

LEFT = -1RIGHT = 1UP = -WIDTH # 一维数组，所以需要整个宽度都加上才能表示上下移动。DOWN = WIDTH 

ERR = -2333

board = [0] * FIELD_SIZE #[0,0,0,……]snake = [0] * (FIELD_SIZE+1)snake[HEAD] = 1*WIDTH+1snake_size = 1

tmpboard = [0] * FIELD_SIZEtmpsnake = [0] * (FIELD_SIZE+1)tmpsnake[HEAD] = 1*WIDTH+1tmpsnake_size = 1

food = 4 * WIDTH + 7best_move = ERR

mov = [LEFT, RIGHT, UP, DOWN]                                           score = 1 

def is_cell_free(idx, psize, psnake):    return not (idx in psnake[:psize]) 

def is_move_possible(idx, move):    flag = False    if move == LEFT:        #因为实际范围是13*13,[1,13]*[1,13]，所以idx为1时不能往左跑，此时取余为1所以>1        flag = True if idx%WIDTH > 1 else False    elif move == RIGHT:        #这里的<WIDTH-2跟上面是一样的道理        flag = True if idx%WIDTH < (WIDTH-2) else False    elif move == UP:        #这里向上的判断画图很好理解，因为在[1,13]*[1,13]的实际运动范围外，还有个        #大框是围墙，就是之前说的那几个行列，下面判断向下运动的条件也是类似的        flag = True if idx > (2*WIDTH-1) else False    elif move == DOWN:        flag = True if idx < (FIELD_SIZE-2*WIDTH) else False    return flag

def board_reset(psnake, psize, pboard):    for i in range(FIELD_SIZE):        if i == food:            pboard[i] = FOOD        elif is_cell_free(i, psize, psnake): # 该位置为空            pboard[i] = UNDEFINED        else: # 该位置为蛇身            pboard[i] = SNAKE

def board_BFS(pfood, psnake, pboard):    queue = []    queue.append(pfood)    inqueue = [0] * FIELD_SIZE    found = False    # while循环结束后，除了蛇的身体，    # 其它每个方格中的数字为从它到食物的曼哈顿间距    while len(queue)!=0:         idx = queue.pop(0)#初始时idx是食物的坐标         if inqueue[idx] == 1: continue        inqueue[idx] = 1        for i in range(4):#左右上下            if is_move_possible(idx, mov[i]):                if idx + mov[i] == psnake[HEAD]:                    found = True                if pboard[idx+mov[i]] < SNAKE: # 如果该点不是蛇的身体                    if pboard[idx+mov[i]] > pboard[idx]+1:#小于的时候不管，不然会覆盖已有的路径数据。                        pboard[idx+mov[i]] = pboard[idx] + 1                    if inqueue[idx+mov[i]] == 0:                        queue.append(idx+mov[i])    return found

def choose_shortest_safe_move(psnake, pboard):    best_move = ERR    min = SNAKE    for i in range(4):        if is_move_possible(psnake[HEAD], mov[i]) and pboard[psnake[HEAD]+mov[i]]<min:          #这里判断最小和下面的函数判断最大，都是先赋值，再循环互相比较            min = pboard[psnake[HEAD]+mov[i]]            best_move = mov[i]    return best_move

def is_tail_inside():    global tmpboard, tmpsnake, food, tmpsnake_size    tmpboard[tmpsnake[tmpsnake_size-1]] = 0 # 虚拟地将蛇尾变为食物(因为是虚拟的，所以在tmpsnake,tmpboard中进行)    tmpboard[food] = SNAKE # 放置食物的地方，看成蛇身    result = board_BFS(tmpsnake[tmpsnake_size-1], tmpsnake, tmpboard) # 求得每个位置到蛇尾的路径长度    for i in range(4): # 如果蛇头和蛇尾紧挨着，则返回False。即不能follow_tail，追着蛇尾运动了        if is_move_possible(tmpsnake[HEAD], mov[i]) and tmpsnake[HEAD]+mov[i]==tmpsnake[tmpsnake_size-1] and tmpsnake_size>3:            result = False    return result

def follow_tail():    global tmpboard, tmpsnake, food, tmpsnake_size    tmpsnake_size = snake_size    tmpsnake = snake[:]    board_reset(tmpsnake, tmpsnake_size, tmpboard) # 重置虚拟board    tmpboard[tmpsnake[tmpsnake_size-1]] = FOOD # 让蛇尾成为食物    tmpboard[food] = SNAKE # 让食物的地方变成蛇身    board_BFS(tmpsnake[tmpsnake_size-1], tmpsnake, tmpboard) # 求得各个位置到达蛇尾的路径长度    tmpboard[tmpsnake[tmpsnake_size-1]] = SNAKE # 还原蛇尾    return choose_longest_safe_move(tmpsnake, tmpboard) # 返回运行方向(让蛇头运动1步)

def any_possible_move():    global food , snake, snake_size, board    best_move = ERR    board_reset(snake, snake_size, board)    board_BFS(food, snake, board)    min = SNAKE    for i in range(4):        if is_move_possible(snake[HEAD], mov[i]) and board[snake[HEAD]+mov[i]]<min:            min = board[snake[HEAD]+mov[i]]            best_move = mov[i]    return best_move

def shift_array(arr, size):    for i in range(size, 0, -1):        arr[i] = arr[i-1]def new_food():#随机函数生成新的食物    global food, snake_size    cell_free = False    while not cell_free:        w = random.randint(1, WIDTH-2)        h = random.randint(1, HEIGHT-2)        food = WIDTH*h + w        cell_free = is_cell_free(food, snake_size, snake)    pygame.draw.rect(playSurface,redColour,Rect(18*(food//WIDTH), 18*(food%WIDTH),18,18))

def make_move(pbest_move):    global snake, board, snake_size, score    shift_array(snake, snake_size)    snake[HEAD] += pbest_move    p = snake[HEAD]    for body in snake:#画蛇，身体，头，尾      pygame.draw.rect(playSurface,whiteColour,Rect(18*(body//WIDTH), 18*(body%WIDTH),18,18))    pygame.draw.rect(playSurface,greenColour,Rect(18*(snake[snake_size-1]//WIDTH),18*(snake[snake_size-1]%WIDTH),18,18))    pygame.draw.rect(playSurface,headColour,Rect(18*(p//WIDTH), 18*(p%WIDTH),18,18))    #下面一行是把初始情况会出现的第一个白块bug填掉    pygame.draw.rect(playSurface,(255,255,0),Rect(0,0,18,18))    # 刷新pygame显示层    pygame.display.flip()         # 如果新加入的蛇头就是食物的位置    # 蛇长加1，产生新的食物，重置board(因为原来那些路径长度已经用不上了)    if snake[HEAD] == food:        board[snake[HEAD]] = SNAKE # 新的蛇头        snake_size += 1        score += 1        if snake_size < FIELD_SIZE: new_food()    else: # 如果新加入的蛇头不是食物的位置        board[snake[HEAD]] = SNAKE # 新的蛇头        board[snake[snake_size]] = UNDEFINED # 蛇尾变为UNDEFINED，黑色        pygame.draw.rect(playSurface,blackColour,Rect(18*(snake[snake_size]//WIDTH),18*(snake[snake_size]%WIDTH),18,18))        # 刷新pygame显示层        pygame.display.flip() 

def virtual_shortest_move():    global snake, board, snake_size, tmpsnake, tmpboard, tmpsnake_size, food    tmpsnake_size = snake_size    tmpsnake = snake[:] # 如果直接tmpsnake=snake，则两者指向同一处内存    tmpboard = board[:] # board中已经是各位置到达食物的路径长度了，不用再计算    board_reset(tmpsnake, tmpsnake_size, tmpboard)        food_eated = False    while not food_eated:        board_BFS(food, tmpsnake, tmpboard)            move = choose_shortest_safe_move(tmpsnake, tmpboard)        shift_array(tmpsnake, tmpsnake_size)        tmpsnake[HEAD] += move # 在蛇头前加入一个新的位置        # 如果新加入的蛇头的位置正好是食物的位置        # 则长度加1，重置board，食物那个位置变为蛇的一部分(SNAKE)        if tmpsnake[HEAD] == food:            tmpsnake_size += 1            board_reset(tmpsnake, tmpsnake_size, tmpboard) # 虚拟运行后，蛇在board的位置            tmpboard[food] = SNAKE            food_eated = True        else: # 如果蛇头不是食物的位置，则新加入的位置为蛇头，最后一个变为空格            tmpboard[tmpsnake[HEAD]] = SNAKE            tmpboard[tmpsnake[tmpsnake_size]] = UNDEFINED

def find_safe_way():    global snake, board    safe_move = ERR    # 虚拟地运行一次，因为已经确保蛇与食物间有路径，所以执行有效    # 运行后得到虚拟下蛇在board中的位置，即tmpboard    virtual_shortest_move() # 该函数唯一调用处    if is_tail_inside(): # 如果虚拟运行后，蛇头蛇尾间有通路，则选最短路运行(1步)        return choose_shortest_safe_move(snake, board)    safe_move = follow_tail() # 否则虚拟地follow_tail 1步，如果可以做到，返回true    return safe_move

pygame.init()

fpsClock = pygame.time.Clock()

playSurface = pygame.display.set_mode((270,270))pygame.display.set_caption('贪吃蛇')

playSurface.fill(blackColour)

pygame.draw.rect(playSurface,redColour,Rect(18*(food//WIDTH), 18*(food%WIDTH),18,18))while True:    for event in pygame.event.get():#循环监听键盘和退出事件        if event.type == QUIT:#如果点了关闭            print(score)#游戏结束后打印分数            pygame.quit()            sys.exit()        elif event.type == KEYDOWN:#如果esc键被按下            if event.key==K_ESCAPE:                print(score)#游戏结束后打印分数                pygame.quit()                sys.exit()    # 刷新pygame显示层    pygame.display.flip()      #画围墙，255,255,0是黄色，边框是36是因为，pygame矩形是以边为初始，向四周填充边框    pygame.draw.rect(playSurface,(255,255,0),Rect(0,0,270,270),36)    # 重置距离    board_reset(snake, snake_size, board)    # 如果蛇可以吃到食物，board_BFS返回true    # 并且board中除了蛇身(=SNAKE)，其它的元素值表示从该点运动到食物的最短路径长    if board_BFS(food, snake, board):        best_move  = find_safe_way() # find_safe_way的唯一调用处    else:        best_move = follow_tail()    if best_move == ERR:        best_move = any_possible_move()    # 上面一次思考，只得出一个方向，运行一步    if best_move != ERR: make_move(best_move)    else:        print(score)#游戏结束后打印分数        break    # 控制游戏速度    fpsClock.tick(20)#20看上去速度正好