This PASCAL/Delphi code is converted into HTML using 
     PAS_Colorizator v1.0 (c) 2001 by Alexander Yanuar Koentjara
                                      (lexzeus@hotmail.com) 

{
Path Finding Algorithm : 8 Filling Square

By    : Alexander Yanuar Koentjara (lexzeus@hotmail.com)
        SYSTEM DEVELOPER of www.globalsources.com

Logarithm for searching path, "A" must find "X" surrounding by walls.
If the path is exist, the algorithm will surely find it.
But if the path doesn't exist, it will try to search the nearset spot as possible
from the target.
}

uses crt;
Const MaxX = 80;
      MinX = 1;
      MaxY = 20;
      MinY = 1;
      MaxSquare = 1000;
      XXX  = 9999;
      MaxTask = 30;
      Cup=0;
      Crup=1;
      Cright=2;
      crdown=3;
      cdown=4;
      cldown=5;
      cleft=6;
      clup=7;

type recs = record x,y:byte; end;

type target = record
        ptr : pointer;
        x,y : integer
     End;

var x,y,i,j : integer;
    Mul,Ak  : Target;    { Mul = Start/From, Ak = End/Target }
    Tiles,Til2 : Array[MinX..MaxX,MinY..MaxY] of integer;

procedure ShowAll;
Var i,j:integer;
Begin
  For j:=MinY to MaxY do
      For i:=MinX to MaxX do
          Begin Gotoxy(i,j); textcolor(7);
                If Til2[i,j]=0 then Write('ù') else
                   if Til2[i,j]=2 then write('²') else
                      Begin textcolor(15);Write('Û');end;
          end;
  TextColor(14); Gotoxy(Mul.X,Mul.Y); Write('A');
  TextColor(14); Gotoxy(Ak.X,Ak.Y); Write('X');
End;

Procedure CariPath(Rang:Integer);
Var x,y,i,j : integer;
    Til31      : Array[0..MaxSquare] of recs;
    Til32      : Array[0..MaxSquare] of recs;
    CTil31     : Integer;
    CTil32     : Integer;
    MovingTask : Array[0..MaxTask] of byte;
    NotBerhasil: Boolean;

Procedure Square(a,b,c:integer);
Function Ok(d,e:integer):Boolean;
Begin
  If (MinX<=d) and (d<=MaxX) and (MinY<=e) and (e<=MaxY) and (Tiles[d,e]=xxx)
     and (Til2[d,e]=0) then
         Begin
         Til32[CTil32].X:=d;Til32[CTil32].Y:=e;
         Inc(CTil32);
         Ok:=True; NotBerhasil:=False;
         End else Ok:=False;
End;

Begin
    If Tiles[a,b]=c then
       Begin
         If Ok(a-1,b-1) then Tiles[a-1,b-1]:=c+1;
         If Ok(a  ,b-1) then Tiles[a  ,b-1]:=c+1;
         If Ok(a+1,b-1) then Tiles[a+1,b-1]:=c+1;
         If Ok(a+1,b  ) then Tiles[a+1,b  ]:=c+1;
         If Ok(a+1,b+1) then Tiles[a+1,b+1]:=c+1;
         If Ok(a  ,b+1) then Tiles[a  ,b+1]:=c+1;
         If Ok(a-1,b+1) then Tiles[a-1,b+1]:=c+1;
         If Ok(a-1,b  ) then Tiles[a-1,b  ]:=c+1;
       End;
End;

Procedure BackTrack(var aa,bb,cc:integer);
Begin
   If Tiles[aa+1,bb  ]=cc then Begin MovingTask[cc+1]:=CLeft;  Til2[aa+1,bb  ]:=2; aa:=aa+1; exit; end;
   If Tiles[aa-1,bb  ]=cc then Begin MovingTask[cc+1]:=CRight; Til2[aa-1,bb  ]:=2; aa:=aa-1; exit; end;
   If Tiles[aa  ,bb-1]=cc then Begin MovingTask[cc+1]:=CDown;  Til2[aa  ,bb-1]:=2; bb:=bb-1; exit; end;
   If Tiles[aa  ,bb+1]=cc then Begin MovingTask[cc+1]:=CUp  ;  Til2[aa  ,bb+1]:=2; bb:=bb+1; exit; end;
   If Tiles[aa-1,bb-1]=cc then Begin MovingTask[cc+1]:=CRDown; Til2[aa-1,bb-1]:=2; aa:=aa-1; bb:=bb-1; exit; end;
   If Tiles[aa+1,bb-1]=cc then Begin MovingTask[cc+1]:=CLDown; Til2[aa+1,bb-1]:=2; aa:=aa+1; bb:=bb-1; exit; end;
   If Tiles[aa+1,bb+1]=cc then Begin MovingTask[cc+1]:=CLUp;   Til2[aa+1,bb+1]:=2; aa:=aa+1; bb:=bb+1; exit; end;
   If Tiles[aa-1,bb+1]=cc then Begin MovingTask[cc+1]:=CRUp;   Til2[aa-1,bb+1]:=2; aa:=aa-1; bb:=bb+1; exit; end;
End;

Begin
  Fillchar(Til31,Sizeof(Til31),0);
  Fillchar(Til32,Sizeof(Til32),0);
  Fillchar(MovingTask,Sizeof(MovingTask),9);

  i:=0;
  Tiles[Ak.X,Ak.Y]:=xxx;
  Tiles[Mul.X,Mul.Y]:=0;
  CTil31:=0;   CTil32:=0;
  Til31[0].X:=Mul.X;
  Til31[0].Y:=Mul.Y;
  Repeat
    NotBerhasil:=True;
    For j:=0 to Ctil31 do Square(Til31[j].X,Til31[j].Y,i);
    CTil31:=CTil32;
    CTil32:=0;
    Move(Til32,Til31,2*CTil31);
    Inc(i);
  until (Tiles[Ak.X,Ak.Y]<>xxx) or NotBerhasil;
  If NotBerhasil then
     Begin
       j:=0; i:=1; Tiles[Ak.X,Ak.Y]:=xxx;
       Repeat
         y:=Ak.Y-i; if y<MinY then y:=MinY;
         Repeat
            x:=Ak.X-i; if X<MinX then X:=MinX;
            Repeat
              If Tiles[x,y]<>xxx then j:=1; inc(x);
            Until (x=Ak.X+i) or (x>MaxX) or (j>0); Inc(y);
         Until (y=Ak.Y+i) or (Y>MaxY) or (j>0);
         i:=i+1;
       Until j>0; x:=x-1; y:=y-1;
     Ak.X:=x; Ak.Y:=Y;
     gotoxy(Ak.X,Ak.y);write('#');
     End;
  i:=Tiles[Ak.X,Ak.Y]; x:=Ak.X; y:=Ak.Y;
  MovingTask[0]:=1;
         Repeat
         Dec(i); BackTrack(X,Y,i);
         Until i=0;
  GOTOXY(1,22); i:=1; Clreol;
  Write('Steps : ');
  Repeat
    Write(MovingTask[i]); inc(i);
  until MovingTask[i]>CLUp;
End;

begin
  clrscr; Randomize;

  { making wall }
  Fillchar(Til2,Sizeof(Til2),0);
  for i:=1 to 40 do til2[i,10]:=1;
  for i:=21 to 70 do til2[i,15]:=1;
  for i:=11 to 50 do til2[i,18]:=1;
  for i:=42 to 80 do til2[i,10]:=1;
  for i:=1 to 10 do til2[30,i]:=1;
  for i:=7 to 15 do til2[60,i]:=1;
  for i:=10 to 20 do til2[20,i]:=1;
  for i:=12 to 20 do til2[30,i]:=1;
  for i:=1 to maxy do
      for j:=1 to maxx do Tiles[j,i]:=xxx;

  Repeat
    Ak.X:=Random(MaxX)+1;  Ak.Y:=Random(MaxY)+1;  { locate end position }
    Mul.X:=Random(MaxX)+1; Mul.Y:=Random(MaxY)+1; { locate start position }
  Until (Til2[Ak.X,Ak.Y]=0) and (Til2[Mul.X,Mul.Y]=0);

  ShowAll;
  Readkey;
  CariPath(10);
  ShowAll;
  GOTOXY(1,21);Write('Direction : 0-Up 1-RUp 2-Right 3-RDown 4-Down 5-LDown 6-Left 7-ULeft');
  GOTOXY(1,23);Write(Tiles[Ak.X,Ak.Y],' steps for "A" to get "X".');
  readkey;
end.