#!/usr/bin/perl

use strict;
use warnings;
use constant NEXT => 0;
use constant VAL => 1;

my ($list, $tail);
my($pred, $temp);
$list = $tail = undef;

# insertion. A linked queue.

foreach (1 .. 5) {
	my $node = [undef, $_ * $_];
	if(not defined $tail) {
		$list = $tail = $node;
	} else {
		$tail->[NEXT] = $node;
		$tail = $node;
	}
}
$temp = $list;

# print the values in the list.

while (defined $temp) {
	print $temp->[VAL], "\n";
	$temp = $temp->[NEXT];
}

# deletion

print "Enter element to be destroyed\n";
my $ele = <>;
chomp $ele;
$pred = $list;
$temp = $list->[NEXT];

while (defined $temp) {
	if($temp->[VAL] == $ele) {
		$pred->[NEXT] = $temp->[NEXT];
		print "$temp->[VAL] found!\n";
		$temp->[NEXT] = undef;
		last;
	} else {
		$temp = $temp->[NEXT];
	}
}

print "list after deleting $ele\n";

while (defined $list) {
	print $list->[VAL], "\n";
	$list = $list->[NEXT];
}