"This is a path finder / maze solver algorithm. Written in Quick BASIC. Quick BASIC has a quick, eacy implementation of an idea without worrying about de-referencing pointers and other rubbish. It takes good care of you :~)." Primary E-Mail: drko@ba3d.com ; kristian@ou.edu

The package contains four files.

• MAZE.BAS
• MAZE1.BAS
• MAZE2.BAS
• readme.txt - viewable as a HTML page.
• Download all files as a WinZIP file: maze.zip (9 kBytes)

Example: No GOTO Statement only Structured Loops:

• FOR variable := start number (or set type) TO end number (or set type) DO - can also count down, or in set step e.g. 0, 2, 4...
• REPEAT ... code ... UNTIL
• WHILE ... code ... DO

• micromouse.pas - Main Programme: Prompts user to select maze then calls up sub-procedures to move the turtle graphic around the maze intelligently.
  
  • type:
    JUNCTION_RECORD = RECORD>   x: INTEGER;   y: INTEGER; back: INTEGER; end; { Record }
  • var:
    • name: STRING;
    • any_maze, new_maze: MAZE_ARRAY;
    • choice, key: CHAR;
    • loop, loop2, x_pos, y_pos, x_wall, y_wall, stack, direction, null: INTEGER;
    • is_junction: ARRAY [1..16,1..16] OF BOOLEAN;
    • junction: ARRAY [0..100] OF JUNCTION_RECORD;
    • path: ARRAY [1..50] OF INTEGER;
  • procedure:
    • move (turtle_direction: INTEGER);
    • move_and_log (turtle_direction: INTEGER);
    • goto_next_junction (junction_heading: INTEGER);
    • procedure go_back;
    • block_and_move (turtle_direction: INTEGER);
  • function:
    • goto_and_log (junction_heading: INTEGER):INTEGER;
    Functions can only return one result variable generally BOOLEAN: TRUE or FALSE. Which can be used in:
    • An IF ... Boolean Condition Selection ... THEN ... execute code ... ELSE ... execute alternative code option ...
    • REPEAT / UNTIL loop
    • DO / WHILE loop.
    Example: REPEAT ... code ... UNTIL isQuit ( ... input variables for computation ... ).

  ---

• maze.tpu [ Turbo Pascal Unit ] - sub-library to main programme. Note box characters became garbled. Contains the following:
  
  • const:
    • GREEN = 1; RED = 2; ORANGE = 3;
  • type:
    • MAZE_ARRAY = ARRAY [1..33] OF STRING; - 1..16 rows plus 17 horizontal walls.
  • procedure:
    • init_chicago_maze (var name: STRING; var chicago_maze: MAZE_ARRAY);
    • init_london_maze  (var name: STRING; var chicago_maze: MAZE_ARRAY);
    • init_japan_maze    (var name: STRING; var chicago_maze: MAZE_ARRAY);
    • write_text (name: STRING);
    • draw_maze   (any_maze: MAZE_ARRAY; colour: INTEGER);
    • draw_blocks (any_maze: MAZE_ARRAY; colour: INTEGER); - where paths diverge giving multiple options, up to three N, E, S, W exits because you can't go back the way you came from.
  • function:
    • roadblock_count (x_pos, y_pos: INTEGER; any_maze: MAZE_ARRAY):INTEGER;
    • wall_count          (x_pos, y_pos: INTEGER; any_maze: MAZE_ARRAY):INTEGER;

  ---

• Based on the IEE micromouse robot competition mazes [Institute of Electrical Engineers]:
  • London (1981)
  • Japan (1982)
  • Chicago (1986)

  ---

• Download all files as a WinZIP file: micromouse.zip (19 kBytes)

The above improved version of the maze solver selects exits at random. But on reaching a dead end retraces it's path back to the last junction and blocks off the entrance to that dead end at the junction. Meaning eventually all dead ends are barred and the 'mouse' eventually finds the finish. In ALL cases. A stack is used to store the junctions visited. With dead end junctions being lifted off the stack when totally blocked off i.e. up to three exits with dead ends.

A previous version of this programme didn't have any AI (Artificial Intelliegence) and just picked a new direction at each juction at random. Thus it NEVER EVER reached the finish due to a "Probability Well" always draging it back to the start. Ther probability against must have been astronomical (a goggle - 10 with 100 zeros after it???). It never got nearer than halve way there.

• money.pas Pascal Programme to convert any given sum in money to the optimal number of denominations.
• m_to_i.pas Imperial to Metric Pascal Programme to convert any given weight (in grams) to tons, stones, and ounces.
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• Download all files as a WinZIP file: pas_progs.zip (5 kBytes)