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|
#!perl
################################################################################
=comment
Perl Weekly Challenge 018
=========================
Task #2
-------
Write a script to implement *Priority Queue*. It is like regular *queue* except
each element has a *priority* associated with it. In a priority queue, an
element with high priority is served before an element with low priority. Please
check this [ https://en.wikipedia.org/wiki/Priority_queue |wiki page] for more
informations. It should serve the following operations:
1) *is_empty*: check whether the queue has no elements.
2) *insert_with_priority*: add an element to the queue with an associated
priority.
3) *pull_highest_priority_element*: remove the element from the queue that has
the highest priority, and return it. If two elements have the same
priority, then return element added first.
=cut
################################################################################
#--------------------------------------#
# Copyright © 2019 PerlMonk Athanasius #
#--------------------------------------#
package MyPriorityQueue;
use strict;
use warnings;
use List::Priority;
sub new
{
my ($class, $reverse) = @_;
my $self =
{
implementation => List::Priority->new,
reverse_priority => $reverse // 0,
};
return bless $self, $class;
}
sub is_empty
{
my ($self) = @_;
return $self->{implementation}->size == 0;
}
sub insert_with_priority
{
my ($self, $priority, $scalar) = @_;
my $result = $self->{implementation}->insert($priority, $scalar);
$result eq '1' or die $result;
}
sub pull_highest_priority_element
{
my ($self) = @_;
# If the queue is empty, undef will be returned
return $self->{reverse_priority} ? $self->{implementation}->shift :
$self->{implementation}->pop;
}
################################################################################
1;
################################################################################
|
