From b1beb66bad02cf5c1bb1793c4590acb062b17298 Mon Sep 17 00:00:00 2001
From: Dave Jacoby <jacoby.david@gmail.com>
Date: Thu, 6 Feb 2025 20:43:51 -0500
Subject: Didn't I do 306?

---
 challenge-306/dave-jacoby/perl/ch-1.pl | 36 +++++++++++++++++++++++++
 challenge-306/dave-jacoby/perl/ch-2.pl | 49 ++++++++++++++++++++++++++++++++++
 2 files changed, 85 insertions(+)
 create mode 100644 challenge-306/dave-jacoby/perl/ch-1.pl
 create mode 100644 challenge-306/dave-jacoby/perl/ch-2.pl

diff --git a/challenge-306/dave-jacoby/perl/ch-1.pl b/challenge-306/dave-jacoby/perl/ch-1.pl
new file mode 100644
index 0000000000..901dffcdff
--- /dev/null
+++ b/challenge-306/dave-jacoby/perl/ch-1.pl
@@ -0,0 +1,36 @@
+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+use experimental qw{ say state postderef signatures };
+
+use List::Util qw{ sum0 };
+
+my @examples = (
+
+    [ 2, 5, 3, 6, 4 ],
+    [ 1, 3 ],
+);
+
+for my $example (@examples) {
+    my $ints   = join ', ', $example->@*;
+    my $output = odd_sum( $example->@* );
+    say <<"END";
+    Input:  \@ints = ($ints)
+    Output: $output
+END
+}
+
+sub odd_sum(@ints) {
+    my $output;
+    for my $l ( map { $_ * 2 - 1 } 1 .. $#ints ) {
+        next if $l > scalar @ints;
+        for my $i ( 0 .. $#ints ) {
+            my $end = -1 + $i + $l;
+            next unless defined $ints[$end];
+            my @slice = @ints[ $i .. $end ];
+            $output += sum0(@slice);
+        }
+    }
+    return $output;
+}
diff --git a/challenge-306/dave-jacoby/perl/ch-2.pl b/challenge-306/dave-jacoby/perl/ch-2.pl
new file mode 100644
index 0000000000..fed124329b
--- /dev/null
+++ b/challenge-306/dave-jacoby/perl/ch-2.pl
@@ -0,0 +1,49 @@
+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+use experimental qw{ say state postderef signatures };
+
+use List::Util qw{ first };
+
+my @examples = (
+
+    [ 3, 8, 5, 2, 9, 2 ],
+    [ 3, 2, 5 ],
+);
+
+for my $example (@examples) {
+    my $ints   = join ', ', $example->@*;
+    my $output = last_element( $example->@* );
+    say <<"END";
+    Input:  \@ints = ($ints)
+    Output: $output
+END
+}
+
+sub last_element(@ints) {
+    while ( scalar @ints > 1 ) {
+        my ( $y, $x ) = sort { $b <=> $a } @ints;
+        if ( $x == $y ) {
+            # there's ugly enough that, if I was to rewrite this,
+            # I would separate this into a function, probably.
+            # As a one-off, it isn't worth it.
+            my $ix = first { $ints[$_] == $x } 0 .. $#ints;
+            $ints[$ix] = undef;
+            @ints = grep { defined } @ints;
+            my $iy = first { $ints[$_] == $y } 0 .. $#ints;
+            $ints[$iy] = undef;
+            @ints = grep { defined } @ints;
+        }
+        else {
+            my $yx = $y - $x;
+            my $iy = first { $ints[$_] == $y } 0 .. $#ints;
+            $ints[$iy] = undef;
+            @ints = grep { defined } @ints;
+            my $ix = first { $ints[$_] == $x } 0 .. $#ints;
+            $ints[$ix] = $yx;
+            @ints = grep { defined } @ints;
+        }
+    }
+    return scalar @ints;
+}
-- 
cgit