## Yes, I know it's been done before.  But has it been done this way?

# maze solver - solves a maze (shortest path) from a file or stdin
#
# Takes mazes with their headers in the format:
# Maze #. 1,1-8,8
# (without the initial '# ')
# (grid with # being wall and . being floor, entrance at (1,1), exit at (8,8))
#
# Note that movement cannot occur diagonally, and that the maze wraps
# around, so that the top is adjacent to the bottom and the left side
# is adjacent to the right.  Put walls there if you don't want that.
# The top left corner is (0, 0).
# Also note that in the maze file, all whitespace is ignored.
#
# Prints out the route in the format (row, col) (row, col) ... inclusive of entrance and exit.
# If no route exists, exits with code 1 and prints "No route found."

#!/usr/bin/perl -w
use strict;

my (@maze, $wall, $floor, @in, @out);

chomp ($_ = <>);
tr/ \n\t\f//d;
m<^Maze(.)(.)(\d+),(\d+)-(\d+),(\d+)$> ?
    (($wall, $floor, @in[0,1], @out[0,1]) =
     ($1, $2, $3, $4, $5, $6)) : die "Invalid maze header; stopped";

while (<>)
{
    chomp;
    tr/ \t\n\f//d;
    my @F = split//;
    push @maze, [ ];
    foreach (@F)
    {
	($_ eq $wall) and push @ {$maze[-1]}, [ 0, 0 ];
	($_ eq $floor) and push @ {$maze[-1]}, [ 1, 0 ];
	($_ ne $wall and
	 $_ ne $floor) and die "Unrecognized character: \'$_\'; stopped";
    }
}

(grep { scalar @$_ != scalar @ {$maze[0]} } @maze) and
    die "Number of columns not the same in every row; stopped";

my ($rows, $cols) = (scalar @maze, scalar @ {$maze[0]});
$maze[$in[0]][$in[1]][0] = 0;
$maze[$in[0]][$in[1]][1] = 1;

for (;;)
{
    if ($maze[$out[0]][$out[1]][1])
    {
	my @sol = ();
	my (@c) = ($out[0], $out[1]);
	while ($c[0] != $in[0] or $c[1] != $in[1])
	{
	    push @sol, [ @c ];
	    (@c) = ($maze[$c[0]][$c[1]][1][0],
		    $maze[$c[0]][$c[1]][1][1]);
	}
	push @sol, [ $in[0], $in[1] ];
	@sol = reverse @sol;
	foreach (@sol)
	{
	    print "($$_[0], $$_[1]) ";
	}
	print "\n";
	exit 0;
    }
	
    my ($any) = (0);
    
    foreach my $row (0..($rows-1))
    {
	foreach my $col (0..($cols-1))
	{
	    next if $maze[$row][$col][0];
	    next unless $maze[$row][$col][1];

	    foreach my $rc ([ $row, $col+1 ],
			    [ $row+1, $col ],
			    [ $row, $col-1 ],
			    [ $row-1, $col ])
	    {
		$maze[$$rc[0]][$$rc[1]][0] && !$maze[$$rc[0]][$$rc[1]][1]
		    and ($maze[$$rc[0]][$$rc[1]][0] = 0,
			 $maze[$$rc[0]][$$rc[1]][1] = [ $row, $col ],
			 $any = 1);
	    }
	}
    }
    if ($any == 0)
    {
	print "No route found.\n";
	exit 1;
    }
}