sudoku !
drop table if exists gen9;
create table gen9(z);
insert into gen9 values
('1'),('2'),('3'),('4'),('5'),('6'),('7'),('8'),('9');
drop table if exists initial;
create table initial ( s, ind) ;
insert into initial select sud, instr( sud, ' ') from
(SELECT '53 7 6 195 98 6 8 6 34 8 3 17 2 6 6 28
419 5 8 79' as sud) as q ;
WITH RECURSIVE x( s, ind ) AS
(SELECT s, ind from initial
UNION ALL
SELECT substr( s, 1, ind - 1 ) || z || substr( s, ind + 1 ) as s
,
instr(substr('xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx',1,
ind)
|| substr( s, ind + 1 ), ' ' ) as ind
FROM x inner join gen9 as z
WHERE ind >0
AND NOT EXISTS ( SELECT NULL
FROM gen9 as lp
WHERE
z.z = substr( s, ( (ind - 1 ) / 9 ) * 9 +lp.z, 1 )
--line search
OR
z.z = substr( s, (ind -(9*(( ind - 1)/ 9 ))) - 9 + lp.z
* 9, 1 ) --columns search
OR
z.z = substr( s, (( ind - 1 ) / 3 - 3*(( ( ind - 1 ) / 3
)/ 3) ) * 3 --square column
+ ( ( ind - 1 ) / 27 ) * 27 --
square line
+ lp.z + ( ( lp.z - 1 ) / 3 ) * 6 --
position in square
, 1 )
)
)
select s from x where ind= 0 ;
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