输入是一个长度为“n”的数组。我需要生成数组元素的所有可能组合,包括输入数组中元素较少的所有组合。
IN: j='{A, B, C ..}'
OUT: k='{A, AB, AC, ABC, ACB, B, BA, BC, BAC, BCA..}'
随着重复,所以AB
BA
..
我尝试过这样的事情:
WITH RECURSIVE t(i) AS (SELECT * FROM unnest('{A,B,C}'::text[]))
,cte AS (
SELECT i AS combo, i, 1 AS ct
FROM t
UNION ALL
SELECT cte.combo || t.i, t.i, ct + 1
FROM cte
JOIN t ON t.i > cte.i
)
SELECT ARRAY(SELECT combo FROM cte ORDER BY ct, combo ) AS result;
它正在生成没有重复的组合......所以我需要以某种方式修改它。