Maze generation

Maze generation is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

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Generate and show a maze, using using the simple Depth-first search algorithm.

J

From the picolisp implementation, except without any grid support:

<lang j>maze=:4 :0

 horiz=. 0$~x,y-1
 verti=. 0$~(x-1),y
 unvisited=. 0,0,~|:0,0,~1$~y,x
 path=.,:here=. ?x,y
 while.#path do.
   unvisited=.0 (<1+here)} unvisited
   neighbors=. here+"1 (,-)0 1 ,:1 0
   neighbors=. neighbors #~ (<"1 neighbors+1) {unvisited
   if.#neighbors do.
     next=. ({~ ?@#) neighbors
     if.{.next=here
     do. horiz=.1 (<-:here+next-0 3)} horiz
     else.verti=. 1 (<-:here+next-3 0)} verti end.
     path=.path,here=.next
   else.
     here=.{:path
     path=.}:path
   end.
 end.
 (horiz,.1{.~-x);1 0,verti

)

display=:3 :0

 size=. 2+$>{.y
 text=. (}:1 3$~2*1+{:size)#"1":size$<' '
 'hdoor vdoor'=. 2 4 *L:0 (#&,{@;&i./@$)&.> y
 2 4}._2 _4}.' ' (3 8+L:0 hdoor)} ' ' (vdoor+L:0"0/2 5;2 6;2 7)} text

)</lang>

Example use (with ascii box drawing enabled):

<lang j> display 12 maze 16 + +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ | | | | | + + + +---+ +---+---+ +---+ +---+ +---+---+---+ + | | | | | | | | | | + + +---+ + + +---+ + + + +---+ + +---+ + | | | | | | | | | | | + +---+---+---+ +---+---+---+---+---+ + + +---+ + + | | | | | | | | | | +---+ + +---+---+ +---+---+---+ + + +---+ +---+---+ | | | | | | | | + + +---+---+ +---+---+ + +---+ +---+ +---+---+ + | | | | | | | | | + +---+---+ +---+ + +---+ + +---+---+---+---+ + + | | | | | | | | | +---+---+ + +---+ +---+ +---+---+---+ + +---+---+ + | | | | | | | | | + +---+ + + +---+ +---+---+---+ + + + + + + | | | | | | | | | | + + + + + + + + + +---+---+---+---+---+---+ + | | | | | | | | | | + + + +---+ + +---+---+ + + +---+---+ + + + | | | | | | | | | | | | + + +---+ +---+ +---+---+ +---+ +---+---+---+ + + | | | | | | +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+</lang>

PicoLisp

This solution uses 'grid' from "lib/simul.l" to generate the two-dimensional structure. <lang PicoLisp>(load "@lib/simul.l")

(de maze (DX DY)

  (let Maze (grid DX DY)
     (let Fld (get Maze (rand 1 DX) (rand 1 DY))
        (recur (Fld)
           (for Dir (shuffle '((west . east) (east . west) (south . north) (north . south)))
              (with ((car Dir) Fld)
                 (unless (or (: west) (: east) (: south) (: north))
                    (put Fld (car Dir) This)
                    (put This (cdr Dir) Fld)
                    (recurse This) ) ) ) ) )
     (for (X . Col) Maze
        (for (Y . This) Col
           (set This
              (cons
                 (cons
                    (: west)
                    (or
                       (: east)
                       (and (= Y 1) (= X DX)) ) )
                 (cons
                    (: south)
                    (or
                       (: north)
                       (and (= X 1) (= Y DY)) ) ) ) )
           (=: west)
           (=: east)
           (=: south)
           (=: north) ) )
     Maze ) )

(de display (Maze)

  (disp Maze 0 '((This) "   ")) )</lang>

Output:

: (display (maze 16 12))
    +   +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
 12 |   |           |           |               |                   |
    +   +   +   +   +   +---+   +   +---+---+   +   +---+   +---+   +
 11 |       |   |       |   |       |   |       |   |       |       |
    +   +---+   +---+---+   +---+---+   +   +---+---+   +---+   +---+
 10 |   |   |   |           |       |       |           |       |   |
    +   +   +   +---+   +   +   +   +   +---+---+   +---+   +---+   +
  9 |       |       |   |   |   |       |       |   |       |       |
    +   +---+---+   +   +---+   +---+---+   +   +   +   +---+   +   +
  8 |   |       |   |           |           |       |   |       |   |
    +   +   +   +   +   +---+---+   +---+   +---+---+   +---+   +   +
  7 |   |   |       |           |       |       |       |       |   |
    +---+   +---+---+---+---+   +---+   +---+   +   +---+   +---+   +
  6 |   |       |           |   |       |   |   |           |   |   |
    +   +---+   +---+   +---+   +   +---+   +   +---+---+---+   +   +
  5 |       |       |           |           |   |               |   |
    +---+   +---+   +---+   +---+   +---+---+   +   +---+   +---+   +
  4 |   |       |       |       |   |       |   |       |   |       |
    +   +---+   +---+   +---+   +---+   +   +   +---+---+   +   +---+
  3 |       |       |   |   |           |   |           |   |       |
    +   +---+---+   +   +   +---+---+---+   +---+   +   +   +---+   +
  2 |       |       |   |   |           |       |   |   |           |
    +   +   +   +---+   +   +   +---+   +---+   +---+   +   +---+---+
  1 |   |               |           |                   |
    +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
      a   b   c   d   e   f   g   h   i   j   k   l   m   n   o   p