#!perl
# labir.pl -- maze generator
# Copyright (C) Zsban Ambrus 2001--2009
use warnings; use strict; use 5.010;
my $W = 35;
my $H = 19;
my @a = ([(1)x(3+2*$W)], map({ [1, (0)x(1+2*$W), 1] } 1 .. 1+2*$H), [(1)x(3+2*$W)]);
for my $u (0 .. $H-1) {
	for my $v (0 .. $W-1) {
		$a[2+2*$u][2+2*$v] = 1;
	}
}
my @y = (-1)x($W*$H);
my $C; $C = sub {
	no warnings "recursion";
	my($v) = @_;
	my $w = $y[$v];
	if ($w < 0) {
		return $v;
	} else {
		my $z = &$C($w);
		$y[$v] = $z;
		return $z;
	}
};
my $U = sub {
	my($u, $v) = @_;
	my($c, $d) = (&$C($u), &$C($v));
	$c != $d and
		$y[$c] = $d;
};
while (&$C(0) != &$C($W*$H-1)) {
	my $a = 1 < rand(2);
	my $x = int(rand($H));
	my $y = int(rand($W));
	$a ? $y < $W - 1 : $x < $H - 1 or next;
	my ($u, $v) = (($x+!$a)*$W+($y+$a), $x*$W+$y);
	&$C($u) != &$C($v) || rand(5) < 1 or next; # here's the magic
	&$U($u, $v);
	$a[2+!$a+2*$x][2+$a+2*$y] = 1;
}
for my $r (1 .. 1+2*$H) {
	for my $c (1 .. 1+2*$W) {
		my $o = $a[$r][$c];
		my $v = $a[$r-1][$c] && $a[$r+1][$c];
		my $h = $a[$r][$c-1] && $a[$r][$c+1];
		print(
			2 == $r && 2 == $c ? "@" :
			2*$H == $r && 1+2*$W == $c ? ">" :
			$o ? " " :
			$v ? ($h ? " " : "-") :
			($h ? "|" : "+")
		);
	}
	print "\n";
}
__END__

##</code><code>##

+-------+---+---+-----+---+-----+-+-+-----+-------+-+-+---+---------+-+
|@      |   |   |     |   |     | | |     |       | | |   |         | |
+-- | +-+---+-- | ----+ | | --- | | +-+ +-+-+-+---+ +-+ | | | +---+-+ |
|   | | |             | | |     | |   | | | | |     |   | | | |   |   |
+-+ +-+-+ | --+-+-+   +-+ | +-+ +-+-+ | | +-+ | --+ +-- +-+ +-+-+ | --+
| |       |   | | |   |     | | | | | | |   | |   |           | |     |
+-+ | --+-+-+-+-+ | --+ ----+-+-+-+ +-+ +-- +-+---+ +-- +-- --+-+-- | |
|   |   | | |         |       | | | | | |           |   |     | |   | |
+---+ | +-+-+-----+   | | +-+-+-+-+-+ | +-+ +-- | | +-+-+-- +-+ | --+-+
|   | |   | |     |     | | |   | |   |   | |   | | | |     | |       |
| --+ +---+ +-+ +-+ --+ +-+-+-+ +-+ +-+-+-+ | --+-+ | | +---+ | | +-+ |
|             | |     |   | | |     | | |   |   | |   | |     | | | | |
+-+-- +-+ | +-+ +-+-- +-+-+-+ +-+   | +-+-- +-+-+-+-+-+-+ | +-+ +-+ +-+
| |   | | | |     |     | |     |     | |   | | | | |     | | |   | | |
| +-- +-+ +-+-+-- +-+ | +-+ +-- +-- --+ +---+ | +-+-+ | | +-+ | --+ | |
|       | |   |     | |   | |                   | | | | | |         | |
| +---+-+-+-- +-+ --+ | | +-+-- | | | +-+ | +-+ | | +-+-+ +-+ ----+ +-+
| |   | |       |     | | |     | | | | | | | |   | |   |   |     | | |
+-+-+ +-+-+-+ | +-- | +-+ | | --+-+-+-+-+ +-+ +-+-+ | +-+ --+ | | | +-+
| | |     | | | |   |   | | |   |     |   |     |   | |     | | |   | |
+-+ +-+-- +-+-+ +-+-+---+ +-+-- | ----+-+ | +-- +-+ | |   --+ | +---+ |
|   | |   |     | |     | |           | | | |   | |                   |
+-+ +-+---+ +-- | +-+-+ | | +-------- +-+ | +-+ +-+ +-+ | +-+---- ----+
| |   |     |   |   | | |   |             |   |     | | | | |         |
| | --+ | --+ | | --+ | +-- +---+ --+ +-- | --+-----+-+-+ | | | | | +-+
| |   | |     |     |   |       |   | |   |         | | | |   | | | | |
+-+ | +-+-----+---- +-+-+   | --+---+-+-+ | +---+---+ +-+ +-+-+-+ | | |
| | | | |     |     | |     |       | | |   |   |   |   | | | | | | | |
| | +-+-+ +-- +-- --+-+ | | +---+ --+ +-+ | | +-+-+-+ | | | | | +-+ | |
|     | | |         | | | | |   |   | |   | | |   |   | | |   | | | | |
+-+ +-+-+ +---------+ | +-+-+ --+ --+ | +-+-+-+ | +-+-+ | | +-+ | | | |
| | | |   |         | | | |             | |     | | |   |   |   | |   |
| | | | | | +-----+-+-+ | | | ----+ +-+-+-+ | +-+-+ | | +-+ +-- | | | |
|   |   | | |     | |     | |     | | |   | | | |   | |   |     |   | |
|   +---+-+-+ | | | +---- +-+ ----+-+ +-+-+-+ | +-- | +-+ +-+-- +-- | |
|   |         | |                 |   | |   | | |       |   |   |   | |
+-+ +-- --+---+-+ +-+-- +-+-- --+-+-- | | | | +-+ +-+-+-+ --+ +-+-+-+ |
| |       |     | | |   | |     | |   |   | |   | | | | |   | | | | | >
+-+-------+-----+-+-+---+-+-----+-+---+---+-+---+-+-+-+-+---+-+-+-+-+-+