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|
#!perl
################################################################################
=comment
Perl Weekly Challenge 068
=========================
Task #2
-------
*Reorder List*
=cut
################################################################################
#--------------------------------------#
# Copyright © 2020 PerlMonk Athanasius #
#--------------------------------------#
#===============================================================================
package SinglyLinkedList;
#===============================================================================
use strict;
use warnings;
#-------------------------------------------------------------------------------
sub new
#-------------------------------------------------------------------------------
{
my ($class, @args) = @_;
my $self = { head => undef };
my $curr;
for my $arg (@args)
{
my $node = { datum => $arg, next => undef };
if (defined $curr)
{
$curr = $curr->{next} = $node;
}
else
{
$curr = $self->{head} = $node;
}
}
return bless $self, $class;
}
#-------------------------------------------------------------------------------
sub get_head
#-------------------------------------------------------------------------------
{
my ($self) = @_;
return $self->{head};
}
#-------------------------------------------------------------------------------
sub remove_tail
#-------------------------------------------------------------------------------
{
my ($self) = @_;
my $tail;
if (my $curr = $self->{head})
{
if ($curr->{next})
{
$curr = $curr->{next} while $curr->{next} && $curr->{next}{next};
$tail = $curr->{next};
$curr->{next} = undef;
}
else
{
$tail = $curr;
$self->{head} = undef;
}
}
return $tail;
}
#-------------------------------------------------------------------------------
sub insert
#-------------------------------------------------------------------------------
{
my ($self, $curr, $node_to_add) = @_;
my $old_next;
if (defined $self->{head} && defined $curr && $curr)
{
$old_next = $curr->{next};
$curr->{next} = $node_to_add;
}
else
{
$old_next = $self->{head};
$self->{head} = $node_to_add;
}
$node_to_add->{next} = $old_next;
}
#-------------------------------------------------------------------------------
sub print
#-------------------------------------------------------------------------------
{
my ($self, $title) = @_;
print $title if defined $title;
if (my $curr = $self->{head})
{
while ($curr)
{
print $curr->{datum};
$curr = $curr->{next};
print ' -> ' if defined $curr;
}
}
else
{
print '<empty>';
}
print "\n";
}
################################################################################
1;
################################################################################
|
