1 files changed, 54 insertions, 0 deletions
diff --git a/challenge-055/mohammad-anwar/perl/ch-2a.pl b/challenge-055/mohammad-anwar/perl/ch-2a.pl
new file mode 100644
index 0000000000..109bcc116a
--- /dev/null
+++ b/challenge-055/mohammad-anwar/perl/ch-2a.pl
@@ -0,0 +1,54 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+use Test::More;
+use Test::Deep;
+use Algorithm::Combinatorics qw(permutations);
+
+my $unit_tests = {
+    1 => [ [1] ],
+    2 => [ [2,1] ],
+    3 => [ [2,1,3], [3,1,2] ],
+    4 => [ [2,1,4,3], [3,1,4,2], [3,2,4,1], [4,1,3,2], [4,2,3,1] ],
+};
+
+foreach my $size (sort { $a <=> $b } keys %$unit_tests) {
+    cmp_deeply(fetch_wave_array($size), $unit_tests->{$size}, "array size $size.");
+}
+
+done_testing;
+
+sub fetch_wave_array {
+    my ($N) = @_;
+
+    die "ERROR: Invalid array size [$N]\n" unless ($N =~ /^\d+$/ && $N > 0);
+
+    my $iter = permutations([ 1..$N ]);
+    my $wave = [];
+    while (my $array = $iter->next) {
+        push @$wave, $array if is_wave($array);
+    }
+
+    return $wave;
+}
+
+sub is_wave {
+    my ($array) = @_;
+
+    my $is_wave = 1;
+    foreach my $i (1..$#$array) {
+        ($i % 2)
+        ?
+        ($array->[$i] <= $array->[$i-1])
+        :
+        ($array->[$i] >= $array->[$i-1])
+        and next;
+
+        $is_wave = 0;
+        last;
+    }
+
+    return $is_wave;
+}