3 files changed, 77 insertions, 0 deletions
diff --git a/challenge-323/dave-jacoby/blog.txt b/challenge-323/dave-jacoby/blog.txt
new file mode 100644
index 0000000000..bafd6f74bd
--- /dev/null
+++ b/challenge-323/dave-jacoby/blog.txt
@@ -0,0 +1 @@
+https://jacoby-lpwk.onrender.com/2025/05/29/orders-matter-and-order-matters-weekly-challenge-323.html
diff --git a/challenge-323/dave-jacoby/perl/ch-1.pl b/challenge-323/dave-jacoby/perl/ch-1.pl
new file mode 100644
index 0000000000..2efdfbe718
--- /dev/null
+++ b/challenge-323/dave-jacoby/perl/ch-1.pl
@@ -0,0 +1,32 @@
+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+use experimental qw{ say state postderef signatures };
+
+use List::Util qw{ sum0 };
+
+my @examples = (
+
+    [ "--x", "x++", "x++" ],
+    [ "x++", "++x", "x++" ],
+    [ "x++", "++x", "--x", "x--" ],
+);
+
+for my $example (@examples) {
+    my $operations = join ', ', map { qq{"$_"} } $example->@*;
+    my $output     = increment_decrement($example->@*);
+    say <<"END";
+    Input:  \@operations = ($operations)
+    Output: $output
+END
+}
+
+sub increment_decrement (@operations) {
+    my $value = 0;
+    for my $op ( @operations ) {
+        $value ++ if $op =~ /\+\+/mx;
+        $value -- if $op =~ /\-\-/mx;
+    }
+    return $value;
+}
diff --git a/challenge-323/dave-jacoby/perl/ch-2.pl b/challenge-323/dave-jacoby/perl/ch-2.pl
new file mode 100644
index 0000000000..c910c5e178
--- /dev/null
+++ b/challenge-323/dave-jacoby/perl/ch-2.pl
@@ -0,0 +1,44 @@
+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+use experimental qw{ say state postderef signatures };
+use List::Util   qw{ uniq };
+
+my @examples = (
+
+    { income => 10, tax => [ [ 3, 50 ], [ 7, 10 ], [ 12, 25 ] ] },
+    { income => 2,  tax => [ [ 1, 0 ],  [ 4, 25 ], [ 5,  50 ] ] },
+    { income => 0,  tax => [ [ 2, 50 ] ] },
+);
+
+for my $example (@examples) {
+    my $income = $example->{income};
+    my @tax    = $example->{tax}->@*;
+    my $tax    = join ', ', map { qq{[ $_ ]} }
+        map { join ', ', $_->@* } @tax;
+    my $output = tax_amount($example);
+    say <<"END";
+    Input:  \@income = $income,
+            \@tax = ($tax)
+    Output: $output
+END
+}
+
+sub tax_amount($example) {
+    my $total  = 0;
+    my $income = $example->{income};
+    my @tax    = $example->{tax}->@*;
+    for my $i ( 0 .. $#tax ) {
+        my $bracket = $tax[$i];
+        my ( $upto, $rate ) = $bracket->@*;
+        my $prev = 0;
+        $prev = $i - 1 >= 0 ? $tax[ $i - 1 ][0] : 0;
+        my $subset = 0;
+        if    ( $income >= $upto ) { $subset = $upto - $prev; }
+        elsif ( $income >= $prev ) { $subset = $income - $prev; }
+        my $subtax = $subset * ( $rate / 100 );
+        $total += $subtax;
+    }
+    return sprintf '%.02f', $total;
+}