--- symmetry.pl	2007/08/26 09:20:07	2
+++ symmetry.pl	2007/08/31 15:17:11	12
@@ -26,47 +26,88 @@
 +-+-+-+-+-+-+-+-+
 _BOARD_
 
+my $debug = shift @ARGV || 0;
+
 my @board = map { split(//) } split(/\n/, $board);
+my @trace;
+my @visited = (' ') x ($#board + 1);
 
 # 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 @shapes_found;
+
+my @shapes_start = ( '0,0' ); #( qw/0,0 1,0 0,3/ );
+
 sub draw {
-	my @board = @_;
 	my $o = 0;
-	my $out;
+	my $out = "\n  " . join('',
+		('0 1 2 3 4 5 6 7 8 | ') x 3
+	) . "\n";
 	while ( $o < $#board ) {
-		$out .= join('', @board[ $o .. $o + $ll - 1 ]) . "\n";
+		my $l = '|';
+		if ( $o % ($ll*2) == 0) {
+			my $y = int($o / ($ll*2));
+			$out .= "$y ";
+			$l = $y;
+		} else {
+			$out .= "  ";
+		}
+
+		$out .= join('', @board[ $o .. $o + $ll - 1 ]);
+		$out .= " $l ";
+		$out .= join('', @trace[ $o .. $o + $ll - 1 ]);
+		$out .= " $l ";
+		$out .= join('', @visited[ $o .. $o + $ll - 1 ]);
+		$out .= " $l\n";
 		$o += $ll;
 	}
-	return $out;
-}
 
-print $board, draw( @board );
+	$out .= "\n";
 
-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 = shift @ARGV || 0;
+	return $out;
+}
 
-my @trace = ('x') x ( $#board + 1 );
 sub trace {
-	warn "trace $pos\n";
+	warn "## trace $pos\n";
 	$trace[ $pos ] = $board[ $pos ];
+	$visited[$pos]++;
 }
 
-warn draw( @trace );
-trace;
+sub x_y {
+	my $p = shift;
+
+	$p ||= $pos;
+
+	my $y = int($p / ($ll*2));
+	my $x = int(($p % $ll) / 2);
+
+	warn "## x_y($p) -> $x,$y\n";
+
+#	return ($x,$y) if wantarray;
+	return "$x,$y";
+}
 
 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;
+	warn "move $step $step_name[$step] to ", x_y, "\n";
 }
 
 sub follow {
@@ -77,6 +118,9 @@
 
 my $ok_path = qr/[\|\-]/;
 
+my @corners;
+my $corners_usage;
+
 sub can_turn {
 	my $try_step = shift;
 	die "no step?" unless defined $try_step;
@@ -87,38 +131,124 @@
 
 	my $old = $trace[ $turn_pos ];
 	$trace[ $turn_pos ] = '?';
-	warn "TEST\n",draw( @trace );
+	$trace[ $pos ] = '*';
+	warn "TEST ", x_y($turn_pos), "\n",draw;
 	$trace[ $turn_pos ] = $old;
 
 	if ( $board[ $turn_pos ] =~ $ok_path ) {
-		warn "OK can_turn $try_step $step_name[$try_step] turn_pos = $turn_pos b($board[$turn_pos]) t($trace[$turn_pos])";
+		my $xy = x_y($pos);
+		warn "OK can_turn $try_step $step_name[$try_step] turn_pos = $turn_pos b($board[$turn_pos]) t($trace[$turn_pos]) from $xy\n";
 		$step = $try_step;
+		push @corners, $xy;
+		$corners_usage->{$xy}++;
 		return 1;
 	} else {
-		warn "NOPE can_turn $try_step $step_name[$try_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])\n";
 		return 0;
 	}
 }
 
-while( 1 ) {
+sub show_directions {
+	return 
+		join('',
+			map {
+				substr($step_name[$_],0,1)
+			} @directions
+		)
+	;
+}
+
+sub shape {
 
-	my $next_pos = $pos + $move_by[ $step ];
-	warn "in loop - pos = $pos next_pos = $next_pos step = $step $step_name[$step]\n";
+	my ($x,$y) = @_;
 
-	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;
-		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";
+	$pos = $y * $ll * 2 + $x * 2;
+
+	@trace = ($unknown) x ( $#board + 1 );
+	@directions = ();
+	@corners = ();
+	trace;
+
+	my $len = 0;
+	$step = 0;
+
+	my $usage = $corners_usage->{"$x,$y"} || 0;
+
+	warn "<<< shape from $x,$y [usage: $usage] pos: $pos\n";
+
+	if ( $usage > 4 ) {
+		warn "SKIPPED, usage > 4\n";
+		return 0;
 	}
-	warn draw( @trace );
 
+	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;
+
+		if ( $debug ) {
+			print "WAIT> press enter | ",show_directions; my $foo = <STDIN>;
+		}
+	}
+
+	push @shapes_found, { x => $x, y => $y, len => $len, directions => show_directions };
+
+	warn "### corners: ",join(' ', map { $_ . " [" . $corners_usage->{$_} . "]" } @corners),"\n";
+	warn ">>> ended at $pos, line length: $len, directions traversed: ",show_directions,"\n";
+
+	foreach my $c ( @corners ) {
+		if ( ! grep( /\Q$c\E/, @shapes_start ) ) {
+			warn "INFO: added corner $c as shape start\n";
+			push @shapes_start, $c;
+		}
+	}
+
+	print "WAIT> press enter"; my $foo = <STDIN>;
+
+	return $len;
+}
+
+foreach my $start ( @shapes_start ) {
+	my ($x,$y) = split(/,/,$start);
+	if ( $x < 8 && $y < 8 ) {
+		my $len = shape( split(/,/,$start) );
+		warn "## $start has $len elements\n";
+	} else {
+		warn "SKIPPED $start\n";
+	}
 }
 
-warn "ended at $pos\n";
+sub is_symmetric {
+	my $path = shift || die "no path?";
 
+	my $h = length($path)/2;
+	return 0 if int($h) != $h;
+	my ($l,$r) = ( substr($path,0,$h), substr($path,$h) );
+	$r =~ tr/lrud/rldu/;
+#	warn "$l -- $r\n";
+	return 0 unless $l eq $r;
+	return 1;
+}
+
+print ">>> RESULTS:\n";
+foreach my $r ( @shapes_found ) {
+	printf "%2d,%-2d len: %-4d directions: %s %s\n",
+	$r->{x}, $r->{y}, $r->{len},
+	is_symmetric($r->{directions}) ? 'OK' : '!!',
+	$r->{directions},
+	;
+}