Merge remote-tracking branch 'upstream/master'

1 files changed, 70 insertions, 0 deletions

diff --git a/challenge-202/luca-ferrari/postgresql/ch-2.sql b/challenge-202/luca-ferrari/postgresql/ch-2.sql
new file mode 100644
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+++ b/challenge-202/luca-ferrari/postgresql/ch-2.sql
@@ -0,0 +1,70 @@
+--
+-- Perl Weekly Challenge 202
+-- Task 2
+--
+-- See <https://perlweeklychallenge.org/blog/perl-weekly-challenge-202/>
+--
+
+CREATE SCHEMA IF NOT EXISTS pwc202;
+
+CREATE OR REPLACE FUNCTION
+pwc202.task2_plpgsql( l int[] )
+RETURNS SETOF int[]
+AS $CODE$
+DECLARE
+	cur int;
+	lft int[];
+	rgt int[];
+	idx int;
+	iter int;
+	prev int;
+BEGIN
+
+	CREATE TEMPORARY TABLE IF NOT EXISTS pwc202
+	( lft int[], rgt int[], dim int DEFAULT 0 );
+	TRUNCATE pwc202;
+
+
+	FOR idx IN 1 .. array_length( l, 1 ) - 1 LOOP
+		cur := l[ idx ];
+		IF l[ idx + 1 ] > cur THEN
+		   CONTINUE;
+		END IF;
+
+		lft := NULL;
+		lft := array_append( lft, cur );
+		FOR iter IN idx + 1 .. array_length( l, 1 ) - 1 LOOP
+		    prev := lft[ array_length( lft, 1 ) ];
+		    IF l[ iter ] <= prev THEN
+		       lft := array_append( lft, l[ iter ] );
+		    END IF;
+		    EXIT WHEN l[ iter ] > prev;
+		END LOOP;
+
+		rgt := NULL;
+		IF array_length( lft, 1 ) + idx <= array_length( l, 1 ) THEN
+		   prev := l[ idx + array_length( lft, 1 ) ];
+		   rgt := array_append( rgt, prev );
+		   FOR iter IN array_length( lft, 1 ) + idx + 1 .. array_length( l, 1 )  LOOP
+		      prev := rgt[ array_length( rgt, 1 ) ];
+		      IF l[ iter ] >= prev THEN
+		       rgt := array_append( rgt, l[ iter ] );
+		      END IF;
+		      EXIT WHEN l[ iter ] < prev;
+		   END LOOP;
+		END IF;
+
+		INSERT INTO pwc202
+		VALUES( lft, rgt, array_length( lft, 1 ) + array_length( rgt, 1 ) );
+
+
+
+	END LOOP;
+
+       RETURN QUERY SELECT array_cat( p.lft, p.rgt )
+       FROM pwc202 p
+       ORDER BY dim DESC
+       LIMIT 1;
+END
+$CODE$
+LANGUAGE plpgsql;