Challenge #51 Task #1

1 files changed, 37 insertions, 0 deletions

diff --git a/challenge-051/dave-cross/ch-01.pl b/challenge-051/dave-cross/ch-01.pl
new file mode 100644
index 0000000000..2ab91e554a
--- /dev/null
+++ b/challenge-051/dave-cross/ch-01.pl
@@ -0,0 +1,37 @@
+#!/usr/bin/perl
+#
+# Note: As $a and $b are special variables in Perl, I've used
+# $x, $y and $z instead of $a, $b and $c.
+
+use strict;
+use warnings;
+use feature 'say';
+
+my $target = 0;
+
+my @numbers = sort { $a <=> $b } grep { /^-?\d+$/  } @ARGV;
+
+die "Usage: $0 [list of integers]\n" unless @numbers;
+
+for my $i (0 .. $#numbers - 1) {
+  my $x     = $numbers[$i];
+  my $start = $i + 1;
+  my $end   = $#numbers;
+
+  while ($start < $end) {
+    my $y = $numbers[$start];
+    my $z = $numbers[$end];
+
+    if ($x + $y + $z == $target) {
+      say "($x, $y, $z)";
+      $start++;
+      $end--;
+    } else {
+      if ($x + $y + $z > $target) {
+        $end--;
+      } else {
+	$start++;
+      }
+    }
+  }
+}