# Copyright 2012, 2013, 2014 Kevin Ryde
# This file is part of Math-PlanePath-Toothpick.
#
# Math-PlanePath-Toothpick is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License as published
# by the Free Software Foundation; either version 3, or (at your option) any
# later version.
#
# Math-PlanePath-Toothpick is distributed in the hope that it will be
# useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
# Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with Math-PlanePath-Toothpick. If not, see <http://www.gnu.org/licenses/>.
# math-image --wx --path=LToothpickTree --values=LinesTree --scale=10 --figure=toothpick_L
# A172310
# L-toothpick A172310 A172311 A172312 A172313
package Math::PlanePath::LToothpickTree;
use 5.004;
use strict;
use Carp 'croak';
#use List::Util 'max';
*max = \&Math::PlanePath::_max;
use vars '$VERSION', '@ISA';
$VERSION = 16;
use Math::PlanePath;
@ISA = ('Math::PlanePath');
use Math::PlanePath::Base::Generic
'is_infinite',
'round_nearest';
use Math::PlanePath::Base::Digits
'round_down_pow';
# uncomment this to run the ### lines
# use Smart::Comments;
use constant n_start => 0;
use constant parameter_info_array =>
[ { name => 'start',
share_key => 'start_upstarplus',
display => 'Start',
type => 'enum',
default => 'right',
choices => ['up','star','plus'],
},
];
my @dir8_to_dx = (1,1,0,-1, -1,-1,0,1);
my @dir8_to_dy = (0,1,1,1, 0,-1,-1,-1);
sub new {
my $self = shift->SUPER::new(@_);
$self->{'horiz'} = 0;
my $start = ($self->{'start'} ||= 'up');
$self->{'rotate_list'} = [ -1, 1 ];
my @initial_dir;
if ($start eq 'up') {
@initial_dir = (2);
} elsif ($start eq 'star') {
@initial_dir = (2, 6);
} elsif ($start eq 'plus') {
@initial_dir = (1, 5);
} else {
croak "Unrecognised start: ",$start;
}
foreach my $dir (@initial_dir) {
$self->{'edges'}->{"0,0,$dir"} = 1; # centre
$self->{'edges'}->{_xyd_opposite(0,0,$dir)} = 1;
foreach my $rotate (@{$self->{'rotate_list'}}) {
my $dir = ($dir + $rotate) & 7;
my $ox = $dir8_to_dx[$dir];
my $oy = $dir8_to_dy[$dir];
push @{$self->{'endpoints_x'}}, $ox;
push @{$self->{'endpoints_y'}}, $oy;
push @{$self->{'endpoints_dir'}}, $dir;
$self->{'endpoints_count'}->{"$ox,$oy"}++;
$self->{'edges'}->{"0,0,$dir"} = 1;
$self->{'edges'}->{_xyd_opposite(0,0,$dir)} = 1;
### opposite: _xyd_opposite(0,0,$dir)
if ($dir & 1) {
### cross1: _xyd_cross1(0,0,$dir)
### cross2: _xyd_cross2(0,0,$dir)
$self->{'edges'}->{_xyd_cross1(0,0,$dir)} = 1;
$self->{'edges'}->{_xyd_cross2(0,0,$dir)} = 1;
}
}
}
### $self
$self->{'xy_to_n'} = { '0,0' => 0 };
$self->{'n_to_x'} = [ 0 ];
$self->{'n_to_y'} = [ 0 ];
$self->{'depth_to_n'} = [ 0 ];
$self->{'depth'} = 0;
return $self;
}
sub _extend {
my ($self) = @_;
### _extend() ...
my $edges = $self->{'edges'};
# foreach my $edge (keys %$edges) {
# my ($x,$y,$dir) = split /,/, $edge;
# my $ox = $x + $dir8_to_dx[$dir];
# my $oy = $y + $dir8_to_dy[$dir];
# my $odir = ($dir + 4) & 7;
# my $okey = "$ox,$oy,$odir";
# exists $edges->{$okey} or die "Oops, missing $okey opposite of $edge";;
# }
my $xy_to_n = $self->{'xy_to_n'};
my $endpoints_x = $self->{'endpoints_x'};
my $endpoints_y = $self->{'endpoints_y'};
my $endpoints_dir = $self->{'endpoints_dir'};
my $endpoints_count = $self->{'endpoints_count'};
my @no_extend;
# never extend if would overlap existing edges,
# or if multiple ends meeting
for (my $i = 0; $i <= $#$endpoints_x; $i++) {
my $x = $endpoints_x->[$i];
my $y = $endpoints_y->[$i];
my $dir = $endpoints_dir->[$i];
### endpoint check never: "$x,$y,$dir"
if ($endpoints_count->{"$x,$y"} > 1) {
# undef $endpoints_x->[$i];
$no_extend[$i] = 1;
next;
}
foreach my $rotate (@{$self->{'rotate_list'}}) {
my $dir = ($dir + $rotate) & 7;
### check existing edge: "$x,$y,$dir"
if (exists $edges->{"$x,$y,$dir"}) {
### exclude due to existing edge ...
# undef $endpoints_x->[$i];
$no_extend[$i] = 1;
}
}
}
# find new edges which would be traversed
my %new_edge;
foreach my $i (0 .. $#$endpoints_x) {
my $x = $endpoints_x->[$i];
next if ! defined $x;
my $y = $endpoints_y->[$i];
my $dir = $endpoints_dir->[$i];
$new_edge{"$x,$y,$dir"}++; # centre
$new_edge{_xyd_opposite($x,$y,$dir)}++;
foreach my $rotate (@{$self->{'rotate_list'}}) {
my $dir = ($dir + $rotate) & 7;
$new_edge{"$x,$y,$dir"}++;
$new_edge{_xyd_opposite($x,$y,$dir)}++;
if ($dir & 1) {
$new_edge{_xyd_cross1($x,$y,$dir)}++;
$new_edge{_xyd_cross2($x,$y,$dir)}++;
}
}
}
# no extend if duplicate new edges, but the endpoint remains a candidate
# for later rounds
foreach my $i (0 .. $#$endpoints_x) {
my $x = $endpoints_x->[$i];
next if ! defined $x;
my $y = $endpoints_y->[$i];
my $dir = $endpoints_dir->[$i];
foreach my $rotate (@{$self->{'rotate_list'}}) {
my $dir = ($dir + $rotate) & 7;
my $key = "$x,$y,$dir";
if ($new_edge{$key} > 1) {
$no_extend[$i] = 1;
}
}
}
my @new_endpoints_x = ();
my @new_endpoints_y = ();
my @new_endpoints_dir = ();
my $n_to_x = $self->{'n_to_x'};
my $n_to_y = $self->{'n_to_y'};
my $depth_to_n = $self->{'depth_to_n'};
my $depth = scalar(@$depth_to_n);
push @{$self->{'depth_to_n'}}, scalar(@$n_to_x); # next N which will be added
### $depth
### new depth_to_n: $self->{'depth_to_n'}
# extend these endpoints now
foreach my $i (0 .. $#$endpoints_x) {
my $x = $endpoints_x->[$i];
next if ! defined $x;
my $y = $endpoints_y->[$i];
my $dir = $endpoints_dir->[$i];
### consider extend endpoint: "xy=$x,$y,dir=$dir"
if ($no_extend[$i]) {
### no extend at this depth, but maybe later ...
push @new_endpoints_x, $x;
push @new_endpoints_y, $y;
push @new_endpoints_dir, $dir;
next;
}
### store: "$x,$y N=".scalar(@$n_to_x)
$xy_to_n->{"$x,$y"} = scalar(@$n_to_x);
push @$n_to_x, $x;
push @$n_to_y, $y;
$edges->{"$x,$y,$dir"} = 1; # centre
$self->{'edges'}->{_xyd_opposite($x,$y,$dir)} = 1;
foreach my $rotate (@{$self->{'rotate_list'}}) {
my $dir = ($dir + $rotate) & 7;
$edges->{"$x,$y,$dir"} = 1;
### store edge: "$x,$y,$dir"
if ($dir & 1) {
$edges->{_xyd_cross1($x,$y,$dir)} = 1;
$edges->{_xyd_cross2($x,$y,$dir)} = 1;
### store cross1: _xyd_cross1($x,$y,$dir)
### store cross2: _xyd_cross2($x,$y,$dir)
}
my $ox = $x + $dir8_to_dx[$dir];
my $oy = $y + $dir8_to_dy[$dir];
my $odir = ($dir + 4) & 7; # opposite direction
$edges->{"$ox,$oy,$odir"} = 1;
### store opposite edge: "$ox,$oy,$odir"
push @new_endpoints_x, $ox;
push @new_endpoints_y, $oy;
push @new_endpoints_dir, $dir;
$endpoints_count->{"$ox,$oy"}++;
}
}
if ($self->{'depth_to_n'}->[-1] == scalar(@$n_to_x)) {
### $endpoints_x
die "Oops, no points added";
}
# print "$depth added ",scalar(@$n_to_x) - $self->{'depth_to_n'}->[-1],
# " endpoints now ",scalar(@new_endpoints_x),"\n";
$self->{'endpoints_x'} = \@new_endpoints_x;
$self->{'endpoints_y'} = \@new_endpoints_y;
$self->{'endpoints_dir'} = \@new_endpoints_dir;
$self->{'depth'}++;
}
sub _xyd_opposite {
my ($x,$y,$dir) = @_;
$x += $dir8_to_dx[$dir];
$y += $dir8_to_dy[$dir];
$dir = ($dir + 4) & 7; # opposite direction
return "$x,$y,$dir";
}
sub _xyd_cross1 {
my ($x,$y,$dir) = @_;
$dir = ($dir - 1) & 7; # right -1
$x += $dir8_to_dx[$dir];
$y += $dir8_to_dy[$dir];
$dir = ($dir + 3) & 7; # left +3
return "$x,$y,$dir";
}
sub _xyd_cross2 {
my ($x,$y,$dir) = @_;
$dir = ($dir + 1) & 7; # right -1
$x += $dir8_to_dx[$dir];
$y += $dir8_to_dy[$dir];
$dir = ($dir - 3) & 7; # left +3
return "$x,$y,$dir";
}
my $stop = 725000;
sub n_to_xy {
my ($self, $n) = @_;
### LToothpickTree n_to_xy(): $n
if ($n < 1) { return; }
if (is_infinite($n)) { return ($n,$n); }
if ($n > $stop) {
return;
}
{
my $int = int($n);
### $int
### $n
if ($n != $int) {
my ($x1,$y1) = $self->n_to_xy($int);
my ($x2,$y2) = $self->n_to_xy($int+1);
my $frac = $n - $int; # inherit possible BigFloat
my $dx = $x2-$x1;
my $dy = $y2-$y1;
return ($frac*$dx + $x1, $frac*$dy + $y1);
}
$n = $int; # BigFloat int() gives BigInt, use that
}
while ($#{$self->{'n_to_x'}} < $n) {
_extend($self);
}
### x: $self->{'n_to_x'}->[$n]
### y: $self->{'n_to_y'}->[$n]
return ($self->{'n_to_x'}->[$n],
$self->{'n_to_y'}->[$n]);
}
sub xy_to_n {
my ($self, $x, $y) = @_;
### LToothpickTree xy_to_n(): "$x, $y"
# ### xy_to_n hash: $self->{'xy_to_n'}
$x = round_nearest ($x);
$y = round_nearest ($y);
my $depth = 2 * (abs($x)+abs($y));
if (is_infinite($depth)) {
return ($depth,$depth);
}
for (;;) {
my $n = $self->{'xy_to_n'}->{"$x,$y"};
if (defined $n) {
### return N: $n
return $n;
}
### $depth
if ($self->{'depth'} <= $depth) {
_extend($self);
} else {
return undef;
}
}
}
# T(depth) = 4 * T(depth-1) + 2
# T(depth) = 2 * (4^depth - 1) / 3
# total = T(depth) + 2
# N = (4^depth - 1)*2/3
# 4^depth - 1 = 3*N/2
# 4^depth = 3*N/2 + 1
#
# len=2^depth
# total = (len*len-1)*2/3 + 2
# not exact
sub rect_to_n_range {
my ($self, $x1,$y1, $x2,$y2) = @_;
### LToothpickTree rect_to_n_range(): "$x1,$y1 $x2,$y2"
$x1 = round_nearest ($x1);
$y1 = round_nearest ($y1);
$x2 = round_nearest ($x2);
$y2 = round_nearest ($y2);
my $depth = 4 * max(1,
abs($x1),
abs($x2),
abs($y1),
abs($y2));
return (0, $depth*$depth);
}
sub tree_depth_to_n {
my ($self, $depth) = @_;
my $depth_to_n = $self->{'depth_to_n'};
while ($#$depth_to_n <= $depth) {
_extend($self);
}
return $depth_to_n->[$depth];
}
sub tree_n_to_depth {
my ($self, $n) = @_;
if ($n < 0) {
return undef;
}
if (is_infinite($n)) {
return $n;
}
my $depth_to_n = $self->{'depth_to_n'};
for (my $depth = 1; ; $depth++) {
while ($depth > $#$depth_to_n) {
_extend($self);
}
if ($n < $depth_to_n->[$depth]) {
return $depth-1;
}
}
}
sub tree_n_children {
my ($self, $n) = @_;
### tree_n_children(): $n
my ($x,$y) = $self->n_to_xy($n)
or return;
### $x
### $y
my @n = map { $self->xy_to_n($x+$dir8_to_dx[$_],$y+$dir8_to_dy[$_]) } 0 .. 7;
my $want_depth = $self->tree_n_to_depth($n) + 1;
### $want_depth
### tree_n_children candidates: @n
# ### depths: map {defined $_ && $n_to_depth->[$_]} @n
@n = sort { $a<=>$b }
grep { defined $_ && $self->tree_n_to_depth($_) == $want_depth }
@n;
### found children: @n
return @n;
}
sub tree_n_parent {
my ($self, $n) = @_;
if ($n < 1) {
return undef;
}
$n = int($n);
my ($x,$y) = $self->n_to_xy($n)
or return undef;
my $want_depth = $self->tree_n_to_depth($n) - 1;
### $want_depth
### assert: $want_depth >= 0
foreach my $dir8 (0 .. 7) {
if (defined (my $parent_n = $self->xy_to_n($x + $dir8_to_dx[$dir8],
$y + $dir8_to_dy[$dir8]))) {
### $parent_n
if ($self->tree_n_to_depth($parent_n) == $want_depth) {
### found parent: "dir8=$dir8 parent_n=$parent_n from n=$n"
return $parent_n;
}
}
}
# die "Oops, parent of n=$n not found";
return undef;
}
1;
__END__
=for stopwords eg Ryde Math-PlanePath-Toothpick Ulam Warburton Nstart Nend
=head1 NAME
Math::PlanePath::LToothpickTree -- toothpick sequence
=head1 SYNOPSIS
use Math::PlanePath::LToothpickTree;
my $path = Math::PlanePath::LToothpickTree->new;
my ($x, $y) = $path->n_to_xy (123);
=head1 DESCRIPTION
I<In progress ...>
This is the "toothpick" sequence expanding through the plane by
non-overlapping line segments (toothpicks).
=cut
# math-image --path=LToothpickTree --output=numbers --all --size=65x11
=pod
5
4
3
2
1
<- Y=0
-1
-2
-3
-4
-5
^
-4 -3 -2 -1 X=0 1 2 3 4
=cut
# Each X,Y point is the centre of a three-pronged toothpick. The toothpick is
# vertical on "even" points X+Y==0 mod 2, or horizontal on "odd" points X+Y==1
# mod 2.
#
# Points are numbered by each growth depth at the endpoints, and
# anti-clockwise around when there's a new point at both ends of an existing
# toothpick.
=pod
\ / \ /
\ / \ /
4 3----
\ / \ / /
\ / \ / /
1---- 1----2----
\
\
\ / \ /
\ / \ /
-----8 7----
\ \ / \ /
\ \ / \ /
-----9-----4 3----
/ \ / / /
/ \ / / /
1----2----6----
\ \
\ \
5----
/ \
/ \
=cut
# The start is N=1 and points N=2 and N=3 are added to the two ends of that
# toothpick. Then points N=4,5,6,7 are added at those four ends.
#
# For points N=4,5,6,7 a new toothpick is only added at each far ends, not the
# "inner" positions X=1,Y=0 and X=-1,Y=0. This is because those points are
# the ends of two toothpicks and would overlap. X=1,Y=0 is the end of
# toothpicks N=4 and N=7, and X=-1,Y=0 the ends of N=5,N=6. The rule is that
# when two ends meet like that nothing is added at that point. The end of a
# toothpick is allowed to touch an existing toothpick. The first time this
# happens is N=16. Its left end touches N=4.
#
# The stair-step X=Y,X=Y-1 diagonal N=2,4,8,12,17,25,36,44,49 etc and similar
# in the other quadrants extend indefinitely. The quarters to either side of
# the diagonals are filled in a self-similar fashion.
=head1 FUNCTIONS
See L<Math::PlanePath/FUNCTIONS> for behaviour common to all path classes.
=over 4
=item C<$path = Math::PlanePath::LToothpickTree-E<gt>new ()>
Create and return a new path object.
=back
=cut
# =head2 Tree Methods
#
# =over
#
# =item C<@n_children = $path-E<gt>tree_n_children($n)>
#
# Return the children of C<$n>, or an empty list if C<$n> has no children
# (including when C<$n E<lt> 1>, ie. before the start of the path).
#
# The children are the new toothpicks added at the ends of C<$n> in the next
# depth. This can be none, one or two points.
#
# =cut
#
# # For example N=8 has a single
# # child 12, N=24 has no children, or N=2 has two children 4,5. The way points
# # are numbered means when there's two children they're consecutive N values.
#
# =item C<$num = $path-E<gt>tree_n_num_children($n)>
#
# Return the number of children of C<$n>, or return C<undef> if C<$nE<lt>1>
# (ie. before the start of the path).
#
# =item C<$n_parent = $path-E<gt>tree_n_parent($n)>
#
# Return the parent node of C<$n>, or C<undef> if C<$n E<lt>= 1> (the start of
# the path).
#
# =back
=head1 SEE ALSO
L<Math::PlanePath>,
L<Math::PlanePath::UlamWarburton>
=head1 HOME PAGE
L<http://user42.tuxfamily.org/math-planepath/index.html>
=head1 LICENSE
Copyright 2012, 2013, 2014 Kevin Ryde
This file is part of Math-PlanePath-Toothpick.
Math-PlanePath-Toothpick is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option) any
later version.
Math-PlanePath-Toothpick is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
Public License for more details.
You should have received a copy of the GNU General Public License along with
Math-PlanePath-Toothpick. If not, see <http://www.gnu.org/licenses/>.
=cut