Task 2 done in PostgreSQL

1 files changed, 31 insertions, 0 deletions

diff --git a/challenge-148/luca-ferrari/postgresql/ch-2.sql b/challenge-148/luca-ferrari/postgresql/ch-2.sql
new file mode 100644
index 0000000000..5d178955a1
--- /dev/null
+++ b/challenge-148/luca-ferrari/postgresql/ch-2.sql
@@ -0,0 +1,31 @@
+WITH RECURSIVE
+triplets AS
+(
+        SELECT a::numeric, b::numeric, c::numeric
+        FROM generate_series( 1, 30 ) a
+             , generate_series( 1, 30 ) b
+             , generate_series( 1, 30 ) c
+        ORDER BY a, b, c
+)
+, cardano_sum AS
+(
+        SELECT a, b, c,
+               ( a + b * sqrt( c ) )   AS l
+               ,( a - b * sqrt( c ) )  AS r
+               FROM triplets
+)
+, cardano AS
+(
+        SELECT a, b, c, l, r
+               , CASE WHEN l < 0 THEN -1 ELSE 1 END * pow( abs( l )::numeric, 1/3::numeric )
+               + CASE WHEN r < 0 THEN -1 ELSE 1 END * pow( abs( r )::numeric, 1/3::numeric )
+               AS triplet_sum
+               FROM cardano_sum
+)
+
+SELECT *
+FROM cardano
+WHERE
+abs( 1 - triplet_sum::numeric ) <= 0.0000000001
+LIMIT 5
+;