/********************************************************************************
*File name:SnakeGame3.0.c       
*Description:貪吃蛇游戲源代碼（C語言），采用
*寬度優(yōu)先算法，計(jì)算蛇到食物的最短路徑（時(shí)間復(fù)雜度n^3空間復(fù)雜度n^2），這個(gè)算法遇 *
*到自身圍困情況將失效，無法計(jì)算出最短路徑     *
*********************************************************************************/
#include<stdio.h>
#include<stdlib.h>
#include<Windows.h>
#include<time.h>
#include<math.h>
#include<conio.h>

#define SIZE 25 //定義地圖大小
#define MAX_LENGTH 19 * 19 //定義蛇的最大長度

typedef struct point //地圖上的點(diǎn)的節(jié)點(diǎn)
{
 int r;
 int c;
} point;
typedef struct queue //迭代搜索最短路徑用到的隊(duì)列
{
 point * body[5 * SIZE]; //保存蛇的身體的數(shù)組（棧的深度最大為5 * SIZE）
 int num; //記錄隊(duì)列中節(jié)點(diǎn)數(shù)
 int first_in_pos; //第一個(gè)進(jìn)入隊(duì)列的元素的索引值
} queue;
HANDLE stdOutput; //聲明windows標(biāo)準(zhǔn)輸出句柄

void init(int * length, point * foodAt, int * dir, point body[], char map[][SIZE]); //初始化
int getDir(int dir); //獲取蛇的行進(jìn)方向
int getAIDir(int dir, int length, point body[], point foodAt); //獲取AI判斷得出的行進(jìn)方向
int moveable(point moveTo, int length, point body[]);
int move(point foodAt, int dir, int length, point body[]); //蛇的運(yùn)動(dòng)
void draw(int length, point foodAt, point body[], char map[][SIZE]); //畫圖
void food(point * foodAt, point body[], int length, char map[][SIZE]); //生成食物

//棧相關(guān)的操作
point * pop(queue *queue); //從列隊(duì)取出最先進(jìn)入的點(diǎn)，返回取出點(diǎn)的指針，取出失敗返回NULL
void push(point *point, queue *queue); //推入列隊(duì)中

int main()
{
 char map[SIZE][SIZE]; //定義地圖
 point body[MAX_LENGTH], foodAt; //整個(gè)蛇身體和食物的所在點(diǎn)（body數(shù)組的第一個(gè)值為蛇頭）
 int length; //蛇的實(shí)際長度
 int dir; //行進(jìn)方向
 int rate = 1; //行進(jìn)速率
 int result; //保存蛇運(yùn)動(dòng)的結(jié)果：【死亡】、【得分】、【無】
 init(&length, &foodAt, &dir, body, map); //初始化

 while (1)
 {
 Sleep(100 / rate);
 //dir = getDir(dir); //獲取蛇的行進(jìn)方向
 dir = getAIDir(dir, length, body, foodAt); //獲取AI判斷得出的行進(jìn)方向
 result = move(foodAt, dir, length, body); //蛇的運(yùn)動(dòng)
 if (result == 1) //如果吃到食物
 {
 length++;
 rate = length / 3;
 if (length == MAX_LENGTH)
 {
 printf("您已通關(guān)！");
 break;
 }
 food(&foodAt, body, length, map); //生成食物
 }
 draw(length, foodAt, body, map); //畫圖
 if (result == -1) //如果死亡
 {
 break;
 }

 }
 Sleep(500); 
 printf(" 失敗，此次得分為%d    ", (length - 3) * 100);
 system("pause");
}
void init(int * length, point * foodAt, int * dir, point body[], char map[][SIZE]) //初始化
{
 memset(map, '*', SIZE * SIZE); //初始化地圖
 body[0].r = 3, body[0].c = 2; //初始化蛇的身體
 body[1].r = 2, body[1].c = 2;
 body[2].r = 1, body[2].c = 2;
 *length = 3; //初始長度為3
 *dir = 2; //初始方向向下
 food(foodAt, body, *length, map); //生成食物
 draw(*length, *foodAt, body, map); //畫圖
 printf(" 按下任意鍵開始，用ASDW控制方向，ESC暫停\n");
 _getch();
 srand((unsigned)time(NULL)); //生成隨機(jī)數(shù)種子，備用
 stdOutput = GetStdHandle(STD_OUTPUT_HANDLE); //獲取標(biāo)準(zhǔn)輸出句柄
 CONSOLE_CURSOR_INFO cci;
 cci.bVisible = 0;
 cci.dwSize = 1;
 SetConsoleCursorInfo(stdOutput, &cci);
 COORD coord = { 0, SIZE * 2 + 3 };
}
int getDir(int dir) //獲取蛇的行進(jìn)方向，規(guī)定返回值0代表向上，1代表向右，2代表向下，3代表向左
{
 char key;
 int newDir = dir;
 if (_kbhit())
 {
 key = _getch();
 switch (key)
 {
 case 'A': case 'a': newDir = 3; break;
 case 'S': case 's': newDir = 2; break;
 case 'D': case 'd': newDir = 1; break;
 case 'W': case 'w': newDir = 0; break;
 case 27: _getch(); break;
 }
 }
 if (newDir - dir == 2 || newDir - dir == -2) //蛇不能反向
 {
 newDir = dir;
 }
 return newDir;
}
int getAIDir(int dir, int length, point body[], point foodAt) //獲取AI判斷得出的行進(jìn)方向
{
 static int *shortestPathDir, count = 0; //保存最短路徑的方向（方向的先后順序?yàn)榈剐?，即排在后面的方向先走?

 if (count == 0) //如果最短路徑還沒生成，那么重新生成
 {
 int map_of_steps[SIZE][SIZE]; //保存到達(dá)地圖上某一點(diǎn)的最小步數(shù)
 queue queue = { 0,0 };
 point *last_body = (point *)malloc(length * sizeof(point)); //保存計(jì)算過程中上次蛇的身體位置
 point *next_body; //保存下一次蛇的身體
 point next_point;
 int i, step = 0;
 point moveTo;
 memcpy(last_body, body, length * sizeof(point));
 memset(map_of_steps, 0, SIZE * SIZE * sizeof(int));

 //向隊(duì)列中放入初始body
 push(last_body, &queue);
 push(NULL, &queue); //插入NULL來標(biāo)識寬度優(yōu)先搜索的某一層的結(jié)束
 step++; //用step來表示步數(shù)，也代表層數(shù)

 while (queue.num != 0)
 {
 last_body = pop(&queue);
 if (last_body == NULL) //如果某一層結(jié)束
 {
 if (queue.num != 0) //如果還有下一層的元素
 {
 step++;
 push(NULL, &queue); //插入下一層的結(jié)束標(biāo)志
 continue;
 }
 else
 {
 break;
 }

 }
 for (i = 0; i < 4; i++) //分別檢測四個(gè)方向能否移動(dòng)
 {
 switch (i)
 {
 case 0: moveTo.r = last_body[0].r - 1, moveTo.c = last_body[0].c; break;
 case 1: moveTo.r = last_body[0].r, moveTo.c = last_body[0].c + 1; break;
 case 2: moveTo.r = last_body[0].r + 1, moveTo.c = last_body[0].c; break;
 case 3: moveTo.r = last_body[0].r, moveTo.c = last_body[0].c - 1; break;
 }
 if (moveable(moveTo, length, last_body) && map_of_steps[moveTo.r][moveTo.c] == 0) //如果移向的點(diǎn)之前沒有移到過
    //（即當(dāng)前路徑是到該點(diǎn)的最短路徑），而且該點(diǎn)是moveable的
 {
 map_of_steps[moveTo.r][moveTo.c] = step;
 if (moveTo.r == foodAt.r && moveTo.c == foodAt.c) //如果下一步就可以到達(dá)食物所在點(diǎn)
 {
 //先free一些沒用的動(dòng)態(tài)內(nèi)存
 free(last_body);
 while (queue.num != 0)
 {
 free(pop(&queue));
 }
 goto outer; //跳出循環(huán)
 }
 //生成next_body并將其推入隊(duì)列
 next_body = (point *)malloc(length * sizeof(point));
 for (i = length - 1; i > 0; i--) //移動(dòng)蛇的位置
 {
 next_body[i] = body[i - 1];
 }
 next_body[0] = moveTo; //換一個(gè)頭

 push(next_body, &queue);//推入隊(duì)列

 }
 }
 //free一些沒用的動(dòng)態(tài)內(nèi)存
 free(last_body);
 }
 outer:;
 if (map_of_steps[foodAt.r][foodAt.c] == 0) //如果無法到達(dá)食物所在點(diǎn)，那么按原路走，直到死亡
 {
 return dir;
 }
 //生成shortestPath
 shortestPathDir = (int *)malloc(step * sizeof(int));
 count = step;
 next_point = foodAt;
 for (i = 0; i < step - 1; i++) //利用map_of_steps和下一個(gè)點(diǎn)推知到上一個(gè)點(diǎn)到下一個(gè)點(diǎn)的方向dir
 {
 if (next_point.r + 1 < SIZE && map_of_steps[next_point.r][next_point.c] ==
 map_of_steps[next_point.r + 1][next_point.c] + 1)
 {
 shortestPathDir[i] = 0;
 next_point.r += 1;
 }
 else if (next_point.c - 1 >= 0 && map_of_steps[next_point.r][next_point.c] ==
 map_of_steps[next_point.r][next_point.c - 1] + 1)
 {
 shortestPathDir[i] = 1;
 next_point.c -= 1;
 }
 else if (next_point.r - 1 >= 0 && map_of_steps[next_point.r][next_point.c] ==
 map_of_steps[next_point.r - 1][next_point.c] + 1)
 {
 shortestPathDir[i] = 2;
 next_point.r -= 1;
 }
 else
 {
 shortestPathDir[i] = 3;
 next_point.c += 1;
 }
 }
 //第一步要單獨(dú)判斷（因?yàn)閙ap_of_steps的值為0的點(diǎn)可能是蛇頭，也可能是蛇身，這樣會對蛇第一步方向判斷產(chǎn)生干擾）
 if (body[0].r > next_point.r)
 {
 shortestPathDir[step - 1] = 0;
 }
 else if (body[0].r < next_point.r)
 {
 shortestPathDir[step - 1] = 2;
 }
 else if (body[0].c > next_point.c)
 {
 shortestPathDir[step - 1] = 3;
 }
 else
 {
 shortestPathDir[step - 1] = 1;
 }
 /*printf("\n\n\n");
 int j;
 for (i = 0; i < SIZE; i++)
 {
 for (j = 0; j < SIZE; j++)
 {
 printf("%3d", map_of_steps[i][j]);
 }
 printf("\n");
 }
 printf("\n");*/
 }
 //沿著最短路徑走
 return shortestPathDir[--count];
}
int moveable(point moveTo, int length, point body[]) //判斷是否可以移動(dòng)到moveTo點(diǎn)，能1，不能0
{
 int i;
 for (i = 0; i < length - 1; i++)
 {
 if (moveTo.r == body[i].r && moveTo.c == body[i].c)
 {
 return 0;
 }
 }
 if (moveTo.r < 0 || moveTo.r >= SIZE || moveTo.c < 0 || moveTo.c >= SIZE) //如果超出邊界
 {
 return 0;
 }
 return 1;
}
int move(point foodAt, int dir, int length, point body[]) //蛇的運(yùn)動(dòng)，規(guī)定返回值-1代表死亡，0代表沒有吃到食物，1代表吃到食物
{
 int i, flag = 0;
 point head = body[0];
 switch (dir)
 {
 case 0: head.r -= 1; break;
 case 1: head.c += 1; break;
 case 2: head.r += 1; break;
 case 3: head.c -= 1; break;
 }
 if (head.r < 0 || head.r >= SIZE || head.c < 0 || head.c >= SIZE) //出界了死亡
 {
 return -1;
 }
 for (i = 0; i < length - 1; i++)
 {
 if (head.r == body[i].r && head.c == body[i].c) //咬到了自己死亡
 {
 return -1;
 }
 }
 if (head.r == foodAt.r && head.c == foodAt.c) //吃到了食物
 {
 length++;
 flag = 1; //標(biāo)記一下，便與等下返回值為1
 }
 for (i = length - 1; i > 0; i--) //移動(dòng)蛇的位置
 {
 body[i] = body[i - 1];
 }
 body[0] = head; //換一個(gè)頭
 if (flag == 1)
 {
 return 1;
 }
 return 0;
}
void draw(int length, point foodAt, point body[], char map[][SIZE]) //畫圖
{

 static char bitmap[SIZE + 2][SIZE + 2]; //定義一個(gè)數(shù)組，用于把地圖背景、邊界、蛇、食物都畫上去
 int i, j;
 for (i = 0; i < SIZE; i++) //背景
 {
 for (j = 0; j < SIZE; j++)
 {
 bitmap[i + 1][j + 1] = map[i][j];
 }
 }
 //邊框
 bitmap[0][0] = '0', bitmap[0][SIZE + 1] = '1';
 bitmap[SIZE + 1][0] = '2', bitmap[SIZE + 1][SIZE + 1] = '3';
 for (i = 0; i < SIZE; i++)
 {
 bitmap[0][i + 1] = '4', bitmap[SIZE + 1][i + 1] = '4';
 bitmap[i + 1][0] = '5', bitmap[i + 1][SIZE + 1] = '5';
 }
 bitmap[foodAt.r + 1][foodAt.c + 1] = 'f'; //食物
 bitmap[body[0].r + 1][body[0].c + 1] = 'h'; //蛇頭
 for (i = 1; i < length; i++) //蛇身
 {
 bitmap[body[i].r + 1][body[i].c + 1] = 'b';
 }

 COORD coord = { 0, 0 }; //座標(biāo)0，0
 SetConsoleCursorPosition(stdOutput, coord); //把光標(biāo)設(shè)置到0，0位置
 for (i = 0; i < SIZE + 2; i++)
 {
 for (j = 0; j < SIZE + 2; j++)
 {
 switch (bitmap[i][j])
 {
 case 'f': printf("★"); break;
 case 'b': printf("●"); break;
 case 'h': printf("○"); break;
 case '0': printf("┏"); break;
 case '1': printf("━┓"); break;
 case '2': printf("┗"); break;
 case '3': printf("━┛"); break;
 case '4': printf(" ━"); break;
 case '5': printf("┃ "); break;
 default: printf(" ");
 }
 }
 printf("\n");
 }
}
void food(point * foodAt, point body[], int length, char map[][SIZE]) //生成食物
{
 int i;
 while (1)
 {
 foodAt->r = rand() % SIZE, foodAt->c = rand() % SIZE; //隨機(jī)生成食物位置
 for (i = 0; i < length; i++)
 {
 if (foodAt->r == body[i].r && foodAt->c == body[i].c) //如果該位置在蛇的身體上
 {
 goto retry;
 }
 }
 break;
 retry:;
 }
}

//隊(duì)列相關(guān)的函數(shù)
point * pop(queue *queue) //從隊(duì)列中取出，返回取出點(diǎn)的指針
{
 queue->num--;
 if (queue->first_in_pos == 5 * SIZE - 1) //返回第一進(jìn)入隊(duì)列的點(diǎn)，并將變量fist_in_pos改變
 {
 queue->first_in_pos = 0;
 return queue->body[5 * SIZE - 1];
 }
 else
 {
 return queue->body[queue->first_in_pos++];
 }
}
void push(point * body, queue *queue)
{
 if (queue->num == 0) //如果隊(duì)列已空
 {
 queue->num++;
 queue->first_in_pos = 0; //將第一進(jìn)入隊(duì)列的位置設(shè)為0
 queue->body[queue->first_in_pos] = body;
 }
 else //否則插入隊(duì)列
 {
 if (queue->first_in_pos + queue->num > 5 * SIZE - 1)
 {
 queue->body[queue->first_in_pos + queue->num++ - 5 * SIZE] = body;
 }
 else
 {
 queue->body[queue->first_in_pos + queue->num++] = body;
 }
 }
}