--- symmetry.pl	2007/08/26 14:15:26	6
+++ symmetry.pl	2007/08/31 15:17:11	12
@@ -87,54 +87,15 @@
 	$visited[$pos]++;
 }
 
-my ( $tr_x, $tr_y );
-my ( $bl_x, $bl_y );
-
 sub x_y {
 	my $p = shift;
 
-	my $update = 0;
-	if ( ! defined( $p ) ) {
-		$p = $pos;
-		$update = 1;
-	}
+	$p ||= $pos;
 
 	my $y = int($p / ($ll*2));
 	my $x = int(($p % $ll) / 2);
 
-	warn "??? x_y($p) $x,$y tr: $tr_x,$tr_y bl: $bl_x,$bl_y\n";
-
-	if ( $update ) {
-
-#		$tr_x = $x if $x > $tr_x && $y == $tr_y;
-#		$tr_y = $y if $y < $tr_y && $x == $tr_x;
-
-		if (
-			$y < $tr_y
-			||
-			$y <= $tr_y && $x > $tr_x
-		) {
-			( $tr_x, $tr_y ) = ( $x, $y );
-			warn "## UPDATED tr: $tr_x,$tr_y\n";
-		}
-
-		if (
-			$x < $bl_x
-			||
-			$y > $bl_y
-		) {
-			( $bl_x, $bl_y ) = ( $x, $y );
-			warn "## UPDATED bl: $bl_x,$bl_y\n";
-		}
-
-#		$bl_x = $x if $x < $bl_x; # && $y == $bl_y;
-#		$bl_y = $y if $y > $bl_y; # && $x == $bl_x;
-	
-	}
-
-	warn "## x_y($p) -> $x,$y ",
-		$update ? " tr: $tr_x,$tr_y bl: $bl_x,$bl_y" : '',
-		"\n";
+	warn "## x_y($p) -> $x,$y\n";
 
 #	return ($x,$y) if wantarray;
 	return "$x,$y";
@@ -157,6 +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;
@@ -172,8 +136,11 @@
 	$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])\n";
+		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])\n";
@@ -199,19 +166,20 @@
 
 	@trace = ($unknown) x ( $#board + 1 );
 	@directions = ();
+	@corners = ();
 	trace;
 
 	my $len = 0;
-	( $tr_x, $tr_y ) = ( $x,$y );
-	( $bl_x, $bl_y ) = ( $x,$y );
 	$step = 0;
 
-	if ( $visited[$pos] > 3 ) {
-		warn "*** shape from $x,$y pos: $pos iterated 4 times, skipping\n";
-		return;
-	}
+	my $usage = $corners_usage->{"$x,$y"} || 0;
 
-	warn "<<< shape from $x,$y pos: $pos\n";
+	warn "<<< shape from $x,$y [usage: $usage] pos: $pos\n";
+
+	if ( $usage > 4 ) {
+		warn "SKIPPED, usage > 4\n";
+		return 0;
+	}
 
 	while( 1 ) {
 
@@ -232,8 +200,6 @@
 		}
 		warn draw;
 
-		warn "## tr: $tr_x,$tr_y bl: $bl_x,$bl_y\n";
-
 		if ( $debug ) {
 			print "WAIT> press enter | ",show_directions; my $foo = <STDIN>;
 		}
@@ -241,18 +207,14 @@
 
 	push @shapes_found, { x => $x, y => $y, len => $len, directions => show_directions };
 
-	my $tr = "$tr_x,$tr_y";
-	my $bl = "$bl_x,$bl_y";
+	warn "### corners: ",join(' ', map { $_ . " [" . $corners_usage->{$_} . "]" } @corners),"\n";
+	warn ">>> ended at $pos, line length: $len, directions traversed: ",show_directions,"\n";
 
-	warn ">>> ended at $pos, line length: $len, directions traversed: ",show_directions," tr: $tr bl: $bl\n";
-
-	if ( ! grep( /\Q$tr\E/, @shapes_start ) && $tr_x < 8 ) {
-		warn "INFO: added $tr top-right\n";
-		push @shapes_start, $tr;
-	}
-	if ( ! grep( /\Q$bl\E/, @shapes_start ) && $bl_y < 8 ) {
-		warn "INFO: added $bl bottom-left\n";
-		push @shapes_start, $bl;
+	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>;
@@ -261,11 +223,32 @@
 }
 
 foreach my $start ( @shapes_start ) {
-	my $len = shape( split(/,/,$start) );
-	warn "## $start has $len elements\n";
+	my ($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";
+	}
+}
+
+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\n", $r->{x}, $r->{y}, $r->{len}, $r->{directions};
+	printf "%2d,%-2d len: %-4d directions: %s %s\n",
+	$r->{x}, $r->{y}, $r->{len},
+	is_symmetric($r->{directions}) ? 'OK' : '!!',
+	$r->{directions},
+	;
 }