--- symmetry.pl	2007/08/26 02:53:41	1
+++ symmetry.pl	2007/08/26 10:59:01	4
@@ -6,8 +6,6 @@
 
 use strict;
 
-use Data::Dump qw/dump/;
-
 my $board = << '_BOARD_';
 +-+-+-+-+-+-+-+-+
 | |   |o| |     |
@@ -28,49 +26,54 @@
 +-+-+-+-+-+-+-+-+
 _BOARD_
 
+my $debug = shift @ARGV || 0;
+
 my @board = map { split(//) } split(/\n/, $board);
+my @trace;
 
 # line length
 my $ll = 8 * 2 + 1;
 
+my @step_name = ( qw/right down left up/ );
+my @move_by = ( 1, $ll, -1, -$ll );
+my $step = 0;	# right
+
+# offset 0, top-left corner
+my $pos = 0;
+
+# unknown trace position
+my $unknown = ' ';
+
+# path traversed
+my @directions;
+
+my @found;
+
 sub draw {
-	my @board = @_;
 	my $o = 0;
 	my $out;
 	while ( $o < $#board ) {
-		$out .= join('', @board[ $o .. $o + $ll - 1 ]) . "\n";
+		$out .= join('', @board[ $o .. $o + $ll - 1 ]);
+		$out .= '   ';
+		$out .= join('', @trace[ $o .. $o + $ll - 1 ]);
+		$out .= "\n";
 		$o += $ll;
 	}
 	return $out;
 }
 
-print $board, draw( @board );
-
-my @step_name = ( qw/right down left up/ );
-my @move_by = ( 1, $ll, -1, -$ll );
-my $step = 0;	# right
-
-# offset 0, top-left corner
-my $pos = 0;
-$pos = 2;
-$pos = 6;
-
-my @trace = ('x') x ( $#board + 1 );
 sub trace {
-	warn "trace $pos\n";
+	warn "## trace $pos\n";
 	$trace[ $pos ] = $board[ $pos ];
 }
 
-warn draw( @trace );
-trace;
-
 sub move {
 	warn "move $step $step_name[$step]\n";
 	$pos += $move_by[ $step ];
 	trace;
 	$pos += $move_by[ $step ];
 	trace;
-	warn draw( @trace );
+	push @directions, $step;
 }
 
 sub follow {
@@ -82,10 +85,12 @@
 my $ok_path = qr/[\|\-]/;
 
 sub can_turn {
-	my $step = shift;
-	die "no step?" unless defined $step;
+	my $try_step = shift;
+	die "no step?" unless defined $try_step;
+
+	$try_step %= 4;
 
-	my $turn_pos = $pos + $move_by[ $step % 4 ];
+	my $turn_pos = $pos + $move_by[$try_step];
 
 	my $old = $trace[ $turn_pos ];
 	$trace[ $turn_pos ] = '?';
@@ -93,40 +98,78 @@
 	$trace[ $turn_pos ] = $old;
 
 	if ( $board[ $turn_pos ] =~ $ok_path ) {
-		warn "OK can_turn $step_name[$step] turn_pos = $turn_pos b($board[$turn_pos]) t($trace[$turn_pos])";
+		warn "OK can_turn $try_step $step_name[$try_step] turn_pos = $turn_pos b($board[$turn_pos]) t($trace[$turn_pos])";
+		$step = $try_step;
 		return 1;
 	} else {
-		warn "NOPE can_turn $step_name[$step] turn_pos = $turn_pos b($board[$turn_pos]) t($trace[$turn_pos])";
+		warn "NOPE can_turn $try_step $step_name[$try_step] turn_pos = $turn_pos b($board[$turn_pos]) t($trace[$turn_pos])";
 		return 0;
 	}
 }
 
-while( 1 ) {
+sub show_directions {
+	return 
+		join('',
+			map {
+				substr($step_name[$_],0,1)
+			} @directions
+		)
+	;
+}
 
-	my $next_pos = $pos + $move_by[ $step ];
-	warn "in loop - pos = $pos next_pos = $next_pos step = $step $step_name[$step]\n";
+sub shape {
 
-	if ( $trace[ $next_pos ] ne 'x' ) {
-		warn "position $next_pos re-visited, exiting\n";
-		last;
-	} elsif ( $board[ $next_pos ] =~ $ok_path ) {
-		warn "OK next_pos = $next_pos b($board[$next_pos]) t($trace[$next_pos])\n";
-		move;
-		follow( $step+1 ) if can_turn( $step+1 );
-	} else {
-		warn "find line continuation from $step $step_name[$step]...\n";
-		foreach my $o ( -1, 1 ) {
-			if ( can_turn( $step + $o ) ) {
-				$step = $step+$o;
-				warn "new direction: $step $step_name[$step]\n";
-				follow( $step );
-				last;
-			}
+	my ($x,$y) = @_;
+
+	$pos = $y * $ll * 2 + $x * 2;
+
+	warn "<<< shape from $x,$y pos: $pos\n";
+	@trace = ($unknown) x ( $#board + 1 );
+	@directions = ();
+	trace;
+
+	my $len = 0;
+
+	while( 1 ) {
+
+		my $next_pos = $pos + $move_by[ $step ];
+		warn "# pos: $pos next_pos: $next_pos step: $step $step_name[$step] trace: ",show_directions,"\n";
+
+		if ( $trace[ $next_pos ] ne $unknown ) {
+			warn "position $next_pos re-visited, exiting\n";
+			last;
+		} elsif ( $board[ $next_pos ] =~ $ok_path ) {
+			warn "OK next_pos = $next_pos b($board[$next_pos]) t($trace[$next_pos])\n";
+			move;
+			$len++;
+			can_turn( $step + 1 );
+		} else {
+			warn "find line continuation from $step $step_name[$step]...\n";
+			can_turn( $step - 1 ) || can_turn( $step + 1 ) || die "can't find new direction";
+		}
+		warn draw( @trace );
+
+		if ( $debug ) {
+			print "WAIT> press enter | ",show_directions; my $foo = <STDIN>;
 		}
 	}
-	warn draw( @trace );
 
+	push @found, { x => $x, y => $y, len => $len, directions => show_directions };
+
+	warn ">>> ended at $pos, line length: $len, directions traversed: ",show_directions,"\n";
+	print "WAIT> press enter"; my $foo = <STDIN>;
+
+	return $len;
 }
 
-warn "ended at $pos\n";
+my $shapes = '0,0 1,0 0,3';
+
+foreach my $start ( split(/\s/,$shapes) ) {
+	my $len = shape( split(/,/,$start) );
+	warn "## $start has $len elements\n";
+}
 
+print ">>> RESULTS:\n";
+foreach my $r ( @found ) {
+	printf "%2d,%-2d len: %-4d directions: %s\n", $r->{x}, $r->{y}, $r->{len}, $r->{directions};
+}