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package BinaryTree;
use strict;
use warnings;
use Data::Dumper qw(Dumper);
use feature qw(say);
## The tree is stored in an array ref
# The first element is the value of the node
# The remainder of the array are child sub-trees
#
# Methods:
# ->add_child( $child_tree )
# ->flatten -- flatten list to array.
#
sub new {
my $class = shift;
my $value = shift;
my $self = [ $value, undef, undef ];
bless $self, $class;
}
sub ancestors {
my $self = shift;
my $x = $self;
my @ancestors;
while($x->has_parent) {
push @ancestors, $x;
$x = $x->parent;
}
return @ancestors;
}
sub max_length {
my $self = shift;
my $d = 0;
$d = $self->left->max_length if $self->has_left;
return 1+$d unless $self->has_right;
my $t = $self->right->max_length;
return $t > $d ? 1+$t : 1+$d;
}
sub diameter {
my $self = shift;
my $global = { 'diameter' => 0 };
$self->walk( sub {
my $d = ($_[0]->has_left ? $_[0]->left->max_length : 0 ) +
($_[0]->has_right ? $_[0]->right->max_length : 0 );
$_[1]{'diameter'} = $d if $d > $_[1]->{'diameter'};
}, $global );
return $global->{'diameter'};
}
sub value {
my $self = shift;
return $self->[0];
}
sub left {
my $self = shift;
return $self->[1];
}
sub parent {
my $self = shift;
return $self->[3];
}
sub has_parent {
my $self = shift;
return defined $self->[3];
}
sub right {
my $self = shift;
return $self->[2];
}
sub has_left {
my $self = shift;
return defined $self->[1];
}
sub has_right {
my $self = shift;
return defined $self->[2];
}
sub update {
my( $self, $val ) = @_;
$self->[0] = $val;
return $self;
}
sub add_child_left {
my( $self,$child ) = @_;
$self->[1] = $child;
$child->[3] = $self;
return $self;
}
sub add_child_right {
my( $self,$child ) = @_;
$self->[2] = $child;
$child->[3] = $self;
return $self;
}
## Define walk method....
sub walk {
my $self = shift;
$self->walk_pre( @_ );
return;
}
##
## Pre-order walk process node then the left and right sub-trees
##
sub walk_pre {
my( $self, $fn, $global, $local, $dir ) = @_;
$local = $fn->( $self, $global, $local, $dir||'' );
$self->left->walk_pre( $fn, $global, $local, 'left' ) if $self->has_left;
$self->right->walk_pre( $fn, $global, $local, 'right' ) if $self->has_right;
return;
}
##
## In-order walk process left sub-tree, then the node and finally the right sub-tree
##
sub walk_in {
my( $self, $fn, $global, $local, $dir ) = @_;
$self->left->walk_in( $fn, $global, $local, 'left' ) if $self->has_left;
$local = $fn->( $self, $global, $local, $dir||'' );
$self->right->walk_in( $fn, $global, $local, 'right' ) if $self->has_right;
return;
}
##
## Reverse-order walk process right sub-tree, then the node and finally the left sub-tree
##
sub walk_reverse {
my( $self, $fn, $global, $local, $dir ) = @_;
$self->right->walk_reverse( $fn, $global, $local, 'right' ) if $self->has_right;
$local = $fn->( $self, $global, $local, $dir||'' );
$self->left->walk_reverse( $fn, $global, $local, 'left' ) if $self->has_left;
return;
}
##
## Post-order walk the left and right subtrees before processing the node...
##
sub walk_post {
my( $self, $fn, $global, $local, $dir ) = @_;
$self->left->walk_post( $fn, $global, $local, 'left' ) if $self->has_left;
$self->right->walk_post( $fn, $global, $local, 'right' ) if $self->has_right;
$local = $fn->( $self, $global, $local, $dir||'' );
return;
}
sub flatten {
my( $self,$dump_fn, $method ) = @_;
$dump_fn ||= sub { $_[0] };
$method = $self->can( 'walk_'.($method||'pre') ) || 'walk';
my $arrayref = [];
$self->$method( sub {
my($node,$global) = @_;
push @{$global}, $dump_fn->( $node->value );
}, $arrayref );
return @{$arrayref};
}
sub dump {
my( $self, $dump_fn ) = @_;
$dump_fn ||= sub { $_[0] };
$self->walk( sub {
my( $node, $global, $local, $dir ) = @_;
say join '', $local||'', $dir eq 'left' ? '<' : $dir eq 'right' ? '>' : ' ', ' ', $dump_fn->($node->value);
return $local .= ' ';
}, {}, '', '' );
return;
}
1;
|
