From b91c8355370302f29a2380e43685737ff644b9f2 Mon Sep 17 00:00:00 2001
From: Luca Ferrari <fluca1978@gmail.com>
Date: Mon, 4 Apr 2022 10:21:30 +0200
Subject: Task 1 done in Pl/Perl

---
 challenge-159/luca-ferrari/postgresql/ch-1.plperl | 39 +++++++++++++++++++++++
 challenge-159/luca-ferrari/postgresql/ch-1.sql    |  1 +
 challenge-159/luca-ferrari/postgresql/ch-2.sql    |  1 +
 3 files changed, 41 insertions(+)
 create mode 100644 challenge-159/luca-ferrari/postgresql/ch-1.plperl
 create mode 100644 challenge-159/luca-ferrari/postgresql/ch-1.sql
 create mode 100644 challenge-159/luca-ferrari/postgresql/ch-2.sql

diff --git a/challenge-159/luca-ferrari/postgresql/ch-1.plperl b/challenge-159/luca-ferrari/postgresql/ch-1.plperl
new file mode 100644
index 0000000000..f14fe72613
--- /dev/null
+++ b/challenge-159/luca-ferrari/postgresql/ch-1.plperl
@@ -0,0 +1,39 @@
+CREATE SCHEMA IF NOT EXISTS pwc159;
+
+CREATE OR REPLACE FUNCTION
+pwc159.farey( int )
+RETURNS SETOF text
+AS $CODE$
+   my ($n) = @_;
+
+   my %farey;
+
+   for my $denominator ( 2 .. $n ) {
+       for my $number ( 1 .. $denominator ) {
+
+           # reduce things like 2/4 to 1/2
+          ( $denominator, $number ) /= $number       if ( $denominator % $number == 0 );
+          ( $denominator, $number ) /= $denominator  if ( $number % $denominator == 0 );
+           
+           $farey{ $number/$denominator } = "$number/$denominator";
+       }
+   }
+
+   # bootstrap
+   return_next( '0/1' );
+
+   my %unique_counter;
+   for my $key ( sort keys( %farey ) ) {
+       # ensure only one item is printed out
+       $unique_counter{ $key }++;
+       next if $unique_counter{ $key } > 1;
+       next if $key == 1;  # last term in the sequence
+       
+       return_next( $farey{ $key } );
+   }
+
+   # end term
+   return_next( '1/1' );
+   return undef;
+$CODE$
+LANGUAGE plperl;
diff --git a/challenge-159/luca-ferrari/postgresql/ch-1.sql b/challenge-159/luca-ferrari/postgresql/ch-1.sql
new file mode 100644
index 0000000000..da8824c0c2
--- /dev/null
+++ b/challenge-159/luca-ferrari/postgresql/ch-1.sql
@@ -0,0 +1 @@
+-- Perl Weekly Challenge 159
diff --git a/challenge-159/luca-ferrari/postgresql/ch-2.sql b/challenge-159/luca-ferrari/postgresql/ch-2.sql
new file mode 100644
index 0000000000..da8824c0c2
--- /dev/null
+++ b/challenge-159/luca-ferrari/postgresql/ch-2.sql
@@ -0,0 +1 @@
+-- Perl Weekly Challenge 159
-- 
cgit