C语言手把手教你实现贪吃蛇AI（下）
本文实例为大家分享了C语言实现贪吃蛇AI的具体代码，供大家参考，具体内容如下
1. 目标
这一部分的目标是把之前写的贪吃蛇加入AI功能，即自动的去寻找食物并吃掉。
2. 控制策略
为了保证蛇不会走入“死地”，所以蛇每前进一步都需要检查，移动到新的位置后，能否找到走到蛇尾的路径，如果可以，才可以走到新的位置；否则在当前的位置寻找走到蛇尾的路径，并按照路径向前走一步，开始循环之前的操作，如下图所示。这个策略可以工作，但是并不高效，也可以尝试其他的控制策略，比如易水寒的贪吃蛇AI
运行效果如下:
3. 源代码
需要注意的是，由于mapnode的数据量比较大，这里需要把栈的大小设置大一点，如下图所示，否则会出现栈溢出的情况。
整个项目由以下三个文件组成：
a. snake AI.h
#ifndef SNAKE_H_
#define SNAKE_H_
#include<stdio.h>
#include<Windows.h> //SetConsoleCursorPosition, sleep函数的头函数
#include<time.h> //time()的头函数
#include<malloc.h> //malloc()的头函数
#define N 32 //地图大小
#define snake_mark '#'//表示蛇身
#define food_mark '$'//表示食物
#define sleeptime 50//间隔时间
#define W 10//权重
typedef struct STARNODE{
int x;//节点的x,y坐标
int y;
int G;//该节点的G, H值
int H;
int is_snakebody;//是否为蛇身，是为1，否则为0；
int in_open_table;//是否在open_table中，是为1，否则为0；
int in_close_table;//是否在close_table中，是为1，否则为0；
struct STARNODE* ParentNode;//该节点的父节点
} starnode, *pstarnode;
extern starnode (*mapnode)[N + 4];
extern pstarnode opentable[N*N / 2];
extern pstarnode closetable[N*N / 2];
extern int opennode_count;
extern int closenode_count;
/*表示蛇身坐标的结构体*/
typedef struct SNAKE{
int x; //行坐标
int y; //列坐标
struct SNAKE* next;
}snake_body, *psnake;
extern psnake snake;
extern psnake food;
extern psnake snaketail;
extern psnake nextnode;
void set_cursor_position(int x, int y);
void initial_map();
void initial_mapnode();
void update_mapnode();
void printe_map();
void initial_snake();
void create_food();
int is_food();
void heapadjust(pstarnode a[], int m, int n);
void swap(pstarnode a[], int m, int n);
void crtheap(pstarnode a[], int n);
void heapsort(pstarnode a[], int n);
void insert_opentable(int x1, int y1, pstarnode pcurtnode, psnake endnode);
void find_neighbor(pstarnode pcurtnode, psnake endnode);
int search_short_road(psnake snakehead, psnake endnode);
int search_snaketail(psnake snakehead);
void update_snaketail(psnake snakehead);
void snake_move();
psnake create_tsnake();
void snake_control();
#endif
b. source.cpp
#include"Snake AI.h"
/*控制光标的坐标*/
void set_cursor_position(int x, int y)
{
COORD coord = { x, y };//x表示列，y表示行。
SetConsoleCursorPosition(GetStdHandle(STD_OUTPUT_HANDLE), coord);
}
/*初始化后的地图为 N列 N/2行*/
/*游戏的空间为2至N+1列，1至N/2行*/
void initial_map()
{
int i = 0;
//打印上下边框（每个■占用一行两列）
for (i = 0; i<N / 2 + 2; i++)
{
set_cursor_position(22 * i, 0);
printf("■");
set_cursor_position(22 * i, N / 2 + 1);
printf("■");
}
for (i = 0; i<N / 2 + 2; i++) //打印左右边框
{
set_cursor_position(0, i);
printf("■");
set_cursor_position(N + 2, i);
printf("■");
}
}
//初始化mapnode
void initial_mapnode()
{
int i = 0, j = 0;
for (i = 0; i < N / 2 + 2; i++)
for (j = 0; j < N + 4; j++)
{
mapnode[i][j].G = 0;
mapnode[i][j].H = 0;
mapnode[i][j].in_close_table = 0;
mapnode[i][j].in_open_table = 0;
mapnode[i][j].is_snakebody = 0;
mapnode[i][j].ParentNode = NULL;
mapnode[i][j].x = i;
mapnode[i][j].y = j;
}
}
//初始化mapnode
void update_mapnode()
{
psnake temp = snake;
int x, y;
initial_mapnode();//初始化mapnode
while (temp)
{
x = temp->x;
y = temp->y;
mapnode[x][y].is_snakebody = 1;
temp = temp->next;
}
}
void printe_map()
{
psnake temp = snake;
while (temp)
{
set_cursor_position(temp->y, temp->x);
printf("%c", snake_mark);
temp = temp->next;
}
if (food)
set_cursor_position(food->y, food->x);
printf("%c", food_mark);
set_cursor_position(0, N / 2 + 2);
}
/*初始化蛇身*/
/*蛇身初始化坐标为（8,5）,(8,4), (8,3) */
void initial_snake()
{
int i = 5;//列
int j = N / 4;//行
psnake tsnake = NULL, temp = NULL;
snake = (psnake)malloc(sizeof(snake_body));
(snake)->x = j;
(snake)->y = i;
(snake)->next = NULL;
tsnake = snake;
for (i = 4; i >2; i--)
{
temp = (psnake)malloc(sizeof(snake_body));
(temp)->x = j;
(temp)->y = i;
(temp)->next = NULL;
(tsnake)->next = (temp);
(tsnake) = (tsnake)->next;
}
snaketail = tsnake;
}
//生成食物
void create_food()
{
srand((unsigned)time(NULL));
food->y = rand() % N + 2;//列
food->x = rand() % (N / 2) + 1;//行
//检查食物是否和蛇身重回
update_mapnode();
if (mapnode[food->x][food->y].is_snakebody)
{
create_food();
}
}
//判断是否吃到食物，吃到食物返回 1，否则返回 0；
int is_food()
{
if (snake->x == food->x && snake->y == food->y)
return 1;
return 0;
}
//根据指针所指向的节点的F值，按大顶堆进行调整
void heapadjust(pstarnode a[], int m, int n)
{
int i;
pstarnode temp = a[m];
for (i = 22 * m; i <= n; i *= 2)
{
if (i + 1 <= n && (a[i + 1]->G + a[i + 1]->H)>(a[i]->G + a[i]->H))
{
i++;
}
if ((temp->G + temp->H)>(a[i]->G + a[i]->H))
{
break;
}
a[m] = a[i];
m = i;
}
a[m] = temp;
}
void swap(pstarnode a[], int m, int n)
{
pstarnode temp;
temp = a[m];
a[m] = a[n];
a[n] = temp;
}
void crtheap(pstarnode a[], int n)
{
int i;
for (i = n / 2; i>0; i--)
{
heapadjust(a, i, n);
}
}
void heapsort(pstarnode a[], int n)
{
int i;
crtheap(a, n);
for (i = n; i>1; i--)
{
swap(a, 1, i);
heapadjust(a, 1, i - 1);
}
}
//x1, y1是邻域点坐标
//curtnode是当前点坐标
//endnode是目标点坐标
void insert_opentable(int x1, int y1, pstarnode pcurtnode, psnake endnode)
{
int i = 1;
if (!mapnode[x1][y1].is_snakebody && !mapnode[x1][y1].in_close_table)//如果不是蛇身也不在closetable中
{
if (mapnode[x1][y1].in_open_table)//如果已经在opentable中
{
if (mapnode[x1][y1].G > pcurtnode->G + W)//但是不是最优路径
{
mapnode[x1][y1].G = pcurtnode->G + W;//把G值更新（变小）
mapnode[x1][y1].ParentNode = pcurtnode;//把该邻点的双亲节点更新
//由于改变了opentable中一个点的F值，需要对opentable中的点的顺序进行调整，以满足有序
for (i = 1; i <= opennode_count; i++)
{
if (opentable[i]->x == x1 && opentable[i]->y == y1)
{
break;
}
}
heapsort(opentable, i);
}
}
else//如果不在opentable中，把该点加入opentable中
{
opentable[++opennode_count] = &mapnode[x1][y1];
mapnode[x1][y1].G = pcurtnode->G + W;
mapnode[x1][y1].H = (abs(endnode->x - x1) + abs(endnode->y - y1))*W;
mapnode[x1][y1].in_open_table = 1;
mapnode[x1][y1].ParentNode = pcurtnode;
heapsort(opentable, opennode_count);
}
}
}
//寻找当前点的四邻域点，把符合条件的点加入opentable中
void find_neighbor(pstarnode pcurtnode, psnake endnode)
{
int x;
int y;
x = pcurtnode->x;
y = pcurtnode->y;
if (x + 1 <= N / 2)
{
insert_opentable(x + 1, y, pcurtnode, endnode);
}
if (x - 1 >= 1)
{
insert_opentable(x - 1, y, pcurtnode, endnode);
}
if (y + 1 <= N + 1)
{
insert_opentable(x, y + 1, pcurtnode, endnode);
}
if (y - 1 >= 2)
{
insert_opentable(x, y - 1, pcurtnode, endnode);
}
}
int search_short_road(psnake snakehead, psnake endnode)
{
int is_search_short_road = 0;
opennode_count = 0;
closenode_count = 0;
pstarnode pcurtnode;
pstarnode temp;
pstarnode startnode = &mapnode[snakehead->x][snakehead->y];//startnode指向蛇头所对应的结点
opentable[++opennode_count] = startnode;//起始点加入opentable中
startnode->in_open_table = 1;
startnode->ParentNode = NULL;
startnode->G = 0;
startnode->H = (abs(endnode->x - startnode->x) + abs(endnode->y - startnode->y))*W;
while (1)
{
//取出opentable中第1个节点加入closetable中
if (!opennode_count)//如果opentable已经为空，即没有找到路径
{
//printf("No way");
return is_search_short_road;
}
pcurtnode = opentable[1];
opentable[1] = opentable[opennode_count--];
closetable[++closenode_count] = pcurtnode;
pcurtnode->in_open_table = 0;
pcurtnode->in_close_table = 1;
if (pcurtnode->x == endnode->x && pcurtnode->y == endnode->y)
{
is_search_short_road = 1;
break;
}
find_neighbor(pcurtnode, endnode);
}
if (is_search_short_road)//如果找到，则用nextnode记录蛇头下一步应该移动的位置
{
temp = closetable[closenode_count];
while (temp->ParentNode->ParentNode)
{
temp = temp->ParentNode;
}
nextnode->x = temp->x;
nextnode->y = temp->y;
nextnode->next = NULL;
}
return is_search_short_road;
}
int search_snaketail(psnake snakehead)
{
int t = 0;
update_mapnode();
mapnode[snaketail->x][snaketail->y].is_snakebody = 0;
t = search_short_road(snakehead, snaketail);
mapnode[snaketail->x][snaketail->y].is_snakebody = 1;
return t;
}
//蛇尾向前移动一格，并把原来的蛇尾注销
void update_snaketail(psnake snakehead)
{
psnake temp;
temp = snakehead;
while (temp->next->next)
{
temp = temp->next;
}
snaketail = temp;
temp = temp->next;
mapnode[temp->x][temp->y].is_snakebody = 0;//将蛇尾注销掉
}
//将蛇身移动到指定的位置(nextnode)，并打印出来
void snake_move()
{
psnake snake_head = (psnake)malloc(sizeof(snake_body));
snake_head->x = nextnode->x;
snake_head->y = nextnode->y;
snake_head->next = snake;
snake = snake_head;
if (is_food())//如果是食物
{
create_food();
printe_map();
}
else//不是食物
{
psnake temp = snake_head;
while (temp->next->next)//寻找蛇尾
{
temp = temp->next;
}
snaketail = temp;//更新snaketail的位置
set_cursor_position(temp->next->y, temp->next->x);
printf(" ");//把蛇尾用空格消掉
free(temp->next);//释放蛇尾的内存空间
temp->next = NULL;//将temp的next置成NULL
printe_map();
}
snake=snake_head;
}
psnake create_tsnake()
{
psnake tsnake = (psnake)malloc(sizeof(snake_body));
tsnake->x = nextnode->x;
tsnake->y = nextnode->y;
tsnake->next = NULL;
psnake temp1 = snake;
psnake temp2 = tsnake;
while (temp1!=snaketail)
{
temp2->next = (psnake)malloc(sizeof(snake_body));
temp2->next->x = temp1->x;
temp2->next->y = temp1->y;
temp2->next->next = NULL;
temp1 = temp1->next;
temp2 = temp2->next;
}
return tsnake;
}
void snake_control()
{
int r, t, x, y;
psnake tsnake = NULL;;
while (1)
{
r = 0;
t = 0;
x = 0;
y = 0;
update_mapnode();
r = search_short_road(snake, food);
if (r == 1)//如果能找到到达食物的路径
{
x = nextnode->x;
y = nextnode->y;
tsnake=create_tsnake();
mapnode[x][y].is_snakebody = 1;
t = search_snaketail(tsnake);//走到下一个节点后，能否找到更新后的蛇尾
if (t==1)//如果按照路径走到下一个位置，可以找到蛇尾，就把蛇头移动到下一个位置
{
nextnode->x = x;
nextnode->y = y;
Sleep(sleeptime);
snake_move();
}
else//否则，从该点出发去找蛇尾
{
mapnode[x][y].is_snakebody = 0;
search_snaketail(snake);
Sleep(sleeptime);
snake_move();
}
free(tsnake);
}
else//如果找不到食物
{
search_snaketail(snake);
Sleep(sleeptime);
snake_move();
}
}
}
c. main.cpp
#include"Snake AI.h"
psnake snake = NULL;
psnake food = NULL;
psnake snaketail = NULL;
psnake nextnode = NULL;//蛇头下一步该走的结点
starnode (*mapnode)[N+4]=(starnode(*)[N+4])malloc(sizeof(starnode)*(N/2+2)*(N+4));
pstarnode opentable[N*N / 2];
pstarnode closetable[N*N / 2];
int opennode_count = 0;
int closenode_count = 0;
int main(void)
{
initial_map();
initial_snake();
food = (psnake)malloc(sizeof(snake_body));
nextnode = (psnake)malloc(sizeof(snake_body));
food->next = NULL;
create_food();
food->x = 1;
food->y = 3;
printe_map();
snake_control();
free(food);
free(snake);
free(mapnode);
return 0;
}
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