Challenge 119 Task 1 LK Perl

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diff --git a/challenge-119/lubos-kolouch/perl/ch-1.pl b/challenge-119/lubos-kolouch/perl/ch-1.pl
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+#!/usr/bin/perl 
+#===============================================================================
+#
+#         FILE: ch-1.pl
+#
+#        USAGE: ./ch-1.pl  
+#
+#  DESCRIPTION: Perl Weekly Challenge #119
+#               Task 1 - Swap Nibbles
+#
+#       AUTHOR: Lubos Kolouch
+#      CREATED: 07/04/2021 04:44:33 PM
+#===============================================================================
+
+use strict;
+use warnings;
+
+sub bin2dec {
+    # shamelessly copied from The Perl Cookbook
+    return unpack("N", pack("B32", substr("0" x 32 . shift, -32)));
+}
+
+sub reverse_nibbles {
+    my $what = shift;
+
+    my $binary_what = sprintf ("%b",$what);
+
+    my $first_part = sprintf("%04d", substr $binary_what, 0, -4);
+    my $second_part = sprintf("%04d", substr $binary_what, -4);
+
+    my $reversed_binary = $second_part . $first_part;
+    return bin2dec($reversed_binary);
+}
+
+use Test::More;
+
+is(reverse_nibbles(101), 86);
+is(reverse_nibbles(18), 33);
+
+done_testing;
+