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--
-- Perl Weekly Challenge 247
-- Task 2
--
-- See <https://perlweeklychallenge.org/blog/perl-weekly-challenge-247/>
--
CREATE SCHEMA IF NOT EXISTS pwc247;
CREATE OR REPLACE FUNCTION
pwc247.task2_plpgsql( string text )
RETURNS TABLE( needle text, repetitions int )
AS $CODE$
DECLARE
needle text;
BEGIN
CREATE TEMPORARY TABLE IF NOT EXISTS repetitions( needle text, repetition int );
TRUNCATE repetitions;
FOR i IN 1 .. length( string ) LOOP
needle := substr( string, i, 2 );
INSERT INTO repetitions
SELECT needle, ( SELECT count(*) FROM regexp_matches( string, needle, 'g' )f );
END LOOP;
RETURN QUERY
SELECT *
FROM repetitions
ORDER BY repetition DESC
LIMIT 1;
END
$CODE$
LANGUAGE plpgsql;
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