Task 2 done in plpgsql

1 files changed, 42 insertions, 0 deletions

diff --git a/challenge-159/luca-ferrari/postgresql/ch-2.sql b/challenge-159/luca-ferrari/postgresql/ch-2.sql
index da8824c0c2..d165df2fed 100644
--- a/challenge-159/luca-ferrari/postgresql/ch-2.sql
+++ b/challenge-159/luca-ferrari/postgresql/ch-2.sql
@@ -1 +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;