Merge remote-tracking branch 'upstream/master'

# Conflicts:
#	challenge-160/paulo-custodio/Makefile

4 files changed, 209 insertions, 0 deletions

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..1ebd6c5112
--- /dev/null
+++ b/challenge-159/luca-ferrari/postgresql/ch-1.sql
@@ -0,0 +1,70 @@
+-- Perl Weekly Challenge 159
+
+
+CREATE SCHEMA IF NOT EXISTS pwc159;
+
+
+CREATE OR REPLACE FUNCTION
+pwc159.farey_not_unique( n int )
+RETURNS TABLE( f text, v numeric )
+AS $CODE$
+DECLARE
+     numerator   int;
+     denominator int;
+     dd          int;
+     nn          int;
+BEGIN
+
+        -- bootstrap term
+        SELECT '0/1', 0
+        INTO f, v;
+
+        RETURN NEXT;
+
+
+        FOR denominator IN 2 .. n  LOOP
+            FOR numerator IN  1 .. denominator  LOOP
+                nn := numerator;
+                dd := denominator;
+
+                IF dd % nn = 0 THEN
+                   dd := dd / nn;
+                   nn := 1;
+                END IF;
+
+                IF nn % dd = 0 THEN
+                   nn := nn / dd;
+                   dd := 1;
+                END IF;
+
+                IF nn / dd = 1 THEN
+                   CONTINUE;
+                END IF;
+
+                SELECT nn || '/' || dd, nn/dd::numeric
+                INTO  f, v;
+
+                RETURN NEXT;
+
+            END LOOP;
+        END LOOP;
+
+        -- end term
+        SELECT '1/1', 1
+        INTO f, v;
+
+        RETURN NEXT;
+
+RETURN;
+END
+$CODE$
+LANGUAGE plpgsql;
+
+
+WITH farey AS (
+     SELECT distinct( f ), v
+     FROM pwc159.farey_not_unique( 5 )
+     ORDER BY v
+)
+SELECT f
+FROM farey;
diff --git a/challenge-159/luca-ferrari/postgresql/ch-2.plperl b/challenge-159/luca-ferrari/postgresql/ch-2.plperl
new file mode 100644
index 0000000000..8dce608e5a
--- /dev/null
+++ b/challenge-159/luca-ferrari/postgresql/ch-2.plperl
@@ -0,0 +1,57 @@
+CREATE SCHEMA IF NOT EXISTS pwc159;
+
+/**
+testdb=> select pwc159.mobius( 5 );
+ mobius 
+--------
+     -1
+(1 row)
+
+*/
+CREATE OR REPLACE FUNCTION
+pwc159.mobius( int )
+RETURNS int
+AS $CODE$
+
+   my ( $n ) = @_;
+
+   # a routine to compute the prime
+   # factors of the given number
+   my $prime_factors = sub {
+      my ( $number ) = @_;
+      my %factors;
+
+      my $factor = 2;
+      while (  $number > 1 && $factor <= $number ) {
+            if ( $number % $factor == 0 ) {
+               $factors{ $factor }++;
+               $number /= $factor;
+            }
+            else {
+                 $factor++;
+            }
+      }
+
+      return %factors;
+   };
+
+
+   my %prime_factors = $prime_factors->( $n );
+
+   # to get the unique prime factors I have to "count"
+   # them only once per key
+   my @unique_prime_factors;
+   my $occurrencies_prime_factors = 0;
+   for ( keys %prime_factors ) {
+       push @unique_prime_factors, $_;
+       $occurrencies_prime_factors += $prime_factors{ $_ };
+   }
+
+
+   return 0 if @unique_prime_factors != $occurrencies_prime_factors;
+   return 1 if @unique_prime_factors % 2 == 0;
+   return -1;
+
+
+$CODE$
+LANGUAGE plperl;
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..d165df2fed
--- /dev/null
+++ b/challenge-159/luca-ferrari/postgresql/ch-2.sql
@@ -0,0 +1,43 @@
+-- Perl Weekly Challenge 159
+
+CREATE SCHEMA IF NOT EXISTS  pwc159;
+
+CREATE OR REPLACE FUNCTION
+pwc159.prime_factors( n int )
+RETURNS SETOF int
+AS $CODE$
+DECLARE
+        factor int;
+BEGIN
+        factor := 2;
+
+        WHILE ( factor <= n AND n > 1 ) LOOP
+              IF n % factor = 0 THEN
+                 n := n / factor;
+                 RETURN NEXT factor;
+              ELSE
+                factor := factor + 1;
+              END IF;
+        END LOOP;
+
+        RETURN;
+END
+$CODE$
+LANGUAGE plpgsql;
+
+
+\set n 5
+
+WITH count_prime_factors(  c, cc ) AS
+(
+        SELECT count( distinct pf ), count( pf )
+        FROM pwc159.prime_factors( :n ) pf
+)
+SELECT :n AS number,
+       CASE
+       WHEN c - cc <> 0 THEN 0
+       WHEN c % 2  = 0  THEN 1
+       ELSE -1
+       END
+
+FROM count_prime_factors;