将从迷宫入口到各点的最短路近的集合看作一棵树。用广度遍历
  的方法即可找到出口的最短路近。本程序算法思想来源于求图上一点
  到其余各点最短路近的Dijkstra算法。

 /* 迷宫探路III（最短路径）*/
/* DIJKSTRAMAZE.C */
/* 2003-8-26 */
#include <stdlib.h>
#include <time.h>
#include <math.h>
#include <stdio.h>
#include <graphics.h>
#define N 22
#define M 22
int bg[M][N];
int aa[M][N];
struct pace{
    int pre;
    int x;
    int y;
    int ri;
    int rj;
}road[M*N];
struct pace bestroad[M*N];

void makebg(int,int);
void drawbg(int[][],int,int,int,int,int);
void drawman(int,int,int);
void rect(int,int,int,int);

void main(){/* main()开始 */
int step=20;
int len=10;
int size=20;
int x=0,y=0;
int i=0,j=0;
int gdriver=DETECT,gmode;
char ch;
int direc;
int routelen=0;
int dj[]={-1,1,0,0};
int di[]={0,0,-1,1};
int begin;
int end;
int k;
int t;
int num;
int suc;
int cnt;
int x0;
int y0;
int le;
int tmp;
makebg(M,N);
/*  registerbgidriver(EGAVGA_driver);
 initgraph(&gdriver,&gmode,"c:\turboc2");*/
 initgraph(&gdriver,&gmode,"c:\tc20\bgi");
cleardevice();
setwritemode(XOR_PUT);
settextstyle(1,0,3);
setcolor(GREEN);
outtextxy(100,180,"DIJKSTRA MAZE");
setcolor(BLUE);
setfillstyle(LINE_FILL,BLUE);

/*drawbg(bg,M,N,size,0,0);*/
drawbg(aa,M,N,size,0,0);
setcolor(WHITE);
x+=len;y+=len;
drawman(x,y,len);
x0=x;y0=y;
/* 电脑控制 */
i=j=0;
aa[0][0]=1;
begin=0;
end=0;
road[0].ri=0;
road[0].rj=0;
road[0].x=x0;
road[0].y=y0;
road[0].pre=-1;
le=1;
suc=0;
while(!suc){
cnt=0;
le++;
for(k=begin;k<=end;k++){
    for(t=0;t<4;t++){
        x=road[k].x+dj[t]*step;
        y=road[k].y+di[t]*step ;
        i=road[k].ri+di[t];
        j=road[k].rj+dj[t];
        if(i<M&&i>=0&&j<N&&j>