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#!/usr/bin/perl
# https://theweeklychallenge.org/blog/perl-weekly-challenge-197/#TASK2
#
# You are given a list of integers, @list.
#
# Write a script to perform Wiggle Sort on the given list.
#
# # Wiggle sort would be such as list[0] < list[1] > list[2] < list[3]...
use strict;
use warnings;
# sample input values
my $inputs = [
[1,5,1,1,6,4],
[1,3,2,2,3,1],
[1,2,3,4,5],
[1,1,1,2,2,2,3,3,4,4],
];
# handle all input arrays from sample list above
foreach my $input (@$inputs) {
print "(" . join(", ", @$input) . ") returns (" . join(", ", wiggle_sort(@$input)) . ")\n";
}
# wiggle sort has to jump up and down every time
sub wiggle_sort {
# let's start by sorting all values
my @values = sort {$a <=> $b} @_;
my @result = ();
# by starting in the middle of the sorted array and walking down while at
# the same time starting at the top and wakling down as well, we can always
# make sure we have a bigger and a smaller value next to each other
my $start = int($#values/2);
my ($i, $j) = ($start, $#values);
while($i >= 0 && $j > $start) {
push @result, $values[$i--], $values[$j--];
}
# if we have an odd number of values in the original array, we now have
# one more value to take care of; in this case $i just reached 0 by means of
# the last "$i--" in the loop
push @result, $values[$i] if $i == 0;
return @result;
}
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