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--
-- Perl Weekly Challenge 247
-- Task 1
--
-- See <https://perlweeklychallenge.org/blog/perl-weekly-challenge-247/>
--
CREATE SCHEMA IF NOT EXISTS pwc247;
CREATE OR REPLACE FUNCTION
pwc247.task1_plpgsql( n text[] )
RETURNS TABLE( current_santa text, current_receiver text )
AS $CODE$
DECLARE
remaining int;
BEGIN
CREATE TEMPORARY TABLE IF NOT EXISTS santas( santa text );
CREATE TEMPORARY TABLE IF NOT EXISTS receivers( receiver text );
TRUNCATE santas;
TRUNCATE receivers;
INSERT INTO santas
SELECT unnest( n );
INSERT INTO receivers
SELECT unnest( n );
SELECT count(*)
INTO remaining
FROM santas;
WHILE remaining > 0 LOOP
SELECT santa
INTO current_santa
FROM santas
ORDER BY random()
LIMIT 1;
SELECT receiver
INTO current_receiver
FROM receivers
ORDER BY random()
LIMIT 1;
IF current_receiver = current_santa THEN
CONTINUE;
END IF;
RETURN NEXT;
DELETE FROM santas WHERE santa = current_santa;
DELETE FROM receivers WHERE receiver = current_receiver;
SELECT count(*)
INTO remaining
FROM santas;
END LOOP;
END
$CODE$
LANGUAGE plpgsql;
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