Maze path III (shortest path)

The set of shortest paths from the entrance of the maze to each point is considered as a tree. Traverse with breadth
To find the shortest path of the exit. The algorithm idea of this program comes from finding a point in the figure.
Dijkstra algorithm for the shortest path to the remaining points.

/* Maze path III (shortest path )*/
/* Define stramaze. 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 );
Void drawman (int, int, int );
Void rect (int, int );

Void main () {/* main () start */
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;
/* Computer Control */
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></