#include"stdio.h"
#include"string.h"
#include"stdlib.h"
#include"conio.h"
#include"dos.h"
#include"bios.h"
#include"time.h"
#define WHITE 7
#define BLUE 1
#define BLACK 0

int toward=1;
int finish=1;
int back[2];
struct node
{
	int mm[2];
	node *pnext;
	node *ppre;
};

node *head;
node *end;

void insert(int ne[2])
{
	node *p=head;
	node *pnew=new node;
	pnew->mm[0]=ne[0];
	pnew->mm[1]=ne[1];
	node *puf;
	pnew->ppre=0;
	gotoxy(ne[0],ne[1]);
	cprintf("%c",1);
	if(p==0)
	{
		pnew->pnext=0;
		end=pnew;
		head=pnew;
		return;
	}
	p->ppre=pnew;
	pnew->pnext=p;
	head=pnew;

}

void del()
{
	node *p=end;
	end=p->ppre;
	gotoxy(p->mm[0],p->mm[1]);
	cputs(" ");
	delete p;
}

void go()
{
	int m[2];
	switch(toward)
	{
	case 1:
		m[0]=head->mm[0]+1;
		m[1]=head->mm[1];
		break;
	case 2:
		m[0]=head->mm[0];
		m[1]=head->mm[1]+1;
		break;
	case 3:
		m[0]=head->mm[0]-1;
		m[1]=head->mm[1];
		break;
	case 4:
		m[0]=head->mm[0];
		m[1]=head->mm[1]-1;
		break;
	}
	insert(m);
	if(back[0]==head->mm[0]&&head->mm[1]==back[1])
	{
		finish=1;
		return;
	}
	del();
}


void gamg()
{
	int x,y;
	node *p;
	while(1)
	{
		x=rand()%14+1;
		y=rand()%14+1;
		for(p=head;p!=0;p=p->pnext)
		{
			if(x==p->mm[0]&&y==p->mm[1])
				break;
			if(p->pnext==0)
			{
				back[0]=x;
				back[1]=y;
				gotoxy(x,y);
				cprintf("%c",1);
				return;
			}
		}
	}
}




void main()
{
	clock_t time2;
	clock_t time1=0;


	char key;
	window(20,5,34,19);
	_setcursortype(_NOCURSOR);
	textcolor(BLACK);
	textbackground(WHITE);
	clrscr();

	int a1[2]={3,3};
	int a2[2]={4,3};
	int a3[2]={5,3};
	insert(a1);
	insert(a2);
	insert(a3);

	while(1)
	{
	   	if(finish==1)
		{
			gamg();
			finish=0;
		}
		time2=clock();
		if(time2-time1>10)
		{
			time1=time2;
			go();
		}
		if(bioskey(1)!=0)
		{
			char key1=getch();
			switch(key1)
			{
			case 'a':
				toward=3;
				break;
			case 'd':
				toward=1;
				break;
			case 's':
				toward=2;
				break;
			case '1':
				return;
			case 'w':
				toward=4;
				break;
			}
		}
	}
}