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-- Perl Weekly Challenge 194
-- Task 2
CREATE SCHEMA IF NOT EXISTS pwc194;
CREATE OR REPLACE FUNCTION
pwc194.task2_plpgsql( what text)
RETURNS int
AS $CODE$
DECLARE
t text;
current_max int;
current_min int;
current_count int;
BEGIN
CREATE TEMPORARY TABLE IF NOT EXISTS counter ( l char, c int, PRIMARY KEY(l) );
TRUNCATE counter;
FOR t IN SELECT v FROM regexp_split_to_table( what, '' ) v LOOP
INSERT INTO counter AS cnt ( l, c )
VALUES ( t, 1 )
ON CONFLICT (l)
DO UPDATE SET c = cnt.c + 1;
END LOOP;
SELECT max(c), min(c)
INTO current_max, current_min
FROM counter;
IF current_max - current_min <> 1 THEN
RETURN 0;
END IF;
SELECT count(*)
INTO current_count
FROM counter
WHERE c = current_max;
IF current_count <> 1 THEN
RETURN 0;
END IF;
RETURN 1;
END
$CODE$
LANGUAGE plpgsql;
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