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-- Perl Weekly Challenge 159
CREATE SCHEMA IF NOT EXISTS pwc159;
CREATE OR REPLACE FUNCTION
pwc159.prime_factors( n int )
RETURNS SETOF int
AS $CODE$
DECLARE
factor int;
BEGIN
factor := 2;
WHILE ( factor <= n AND n > 1 ) LOOP
IF n % factor = 0 THEN
n := n / factor;
RETURN NEXT factor;
ELSE
factor := factor + 1;
END IF;
END LOOP;
RETURN;
END
$CODE$
LANGUAGE plpgsql;
\set n 5
WITH count_prime_factors( c, cc ) AS
(
SELECT count( distinct pf ), count( pf )
FROM pwc159.prime_factors( :n ) pf
)
SELECT :n AS number,
CASE
WHEN c - cc <> 0 THEN 0
WHEN c % 2 = 0 THEN 1
ELSE -1
END
FROM count_prime_factors;
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