Task solved as PostgreSQL functions

2 files changed, 57 insertions, 0 deletions

diff --git a/challenge-136/luca-ferrari/postgresql/ch-1.sql b/challenge-136/luca-ferrari/postgresql/ch-1.sql
new file mode 100644
index 0000000000..ed1f0c71a0
--- /dev/null
+++ b/challenge-136/luca-ferrari/postgresql/ch-1.sql
@@ -0,0 +1,24 @@
+/*
+testdb=> SELECT FRIENDLY( 26, 39 );
+friendly
+----------
+0
+(1 row)
+
+testdb=> SELECT FRIENDLY( 26, 52 );
+friendly
+----------
+1
+(1 row)
+
+*/
+CREATE OR REPLACE FUNCTION friendly( m int, n int )
+RETURNS int
+AS $CODE$
+   SELECT
+        CASE gcd( m, n ) % 2
+             WHEN 0  THEN 1
+             ELSE 0
+        END;
+$CODE$
+LANGUAGE SQL;
diff --git a/challenge-136/luca-ferrari/postgresql/ch-2.sql b/challenge-136/luca-ferrari/postgresql/ch-2.sql
new file mode 100644
index 0000000000..e1f6439ec0
--- /dev/null
+++ b/challenge-136/luca-ferrari/postgresql/ch-2.sql
@@ -0,0 +1,33 @@
+CREATE OR REPLACE FUNCTION fibonacci_sum( l int DEFAULT 16 )
+RETURNS bigint
+AS $CODE$
+
+WITH RECURSIVE
+fibonacci( n, p ) AS
+(
+        SELECT 1, 1
+        UNION
+        SELECT p + n, n
+        FROM fibonacci
+        WHERE n < l
+)
+, permutations AS
+(
+        SELECT n::text AS current_value, n as total_sum
+        FROM fibonacci
+        UNION
+        SELECT current_value || ',' || n, total_sum + n
+        FROM permutations, fibonacci
+        WHERE
+                position( n::text in  current_value ) = 0
+       AND n > ALL( string_to_array( current_value, ',' )::int[] )
+
+
+)
+SELECT count(*)
+FROM permutations
+WHERE total_sum = l
+;
+
+$CODE$
+LANGUAGE SQL;