Solve your SUDOKU by SQL!
May 31, 2011 1 Comment
Oracle Database 11g Release 2 introduces a new feature called Recursive Subquery Factoring with the help of which you can solve your Sudoku.
Say you have a Sudoku like:
To solve this Sudoku you first have to transform this to a single string by appending all rows together:(give exact amount of spaces)
Past this string into a Recursive Subquery, run it and you get a new string with your solved Sudoku:
with x( s, ind ) as ( 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' sud from dual ) union all select substr( s, 1, ind - 1 ) || z || substr( s, ind + 1 ) , instr( s, ' ', ind + 1 ) from x , ( select to_char( rownum ) z from dual connect by rownum <= 9 ) z where ind > 0 and not exists ( select null from ( select rownum lp from dual connect by rownum <= 9 ) where z = substr( s, trunc( ( ind - 1 ) / 9 ) * 9 + lp, 1 ) or z = substr( s, mod( ind - 1, 9 ) - 8 + lp * 9, 1 ) or z = substr( s, mod( trunc( ( ind - 1 ) / 3 ), 3 ) * 3 + trunc( ( ind - 1 ) / 27 ) * 27 + lp + trunc( ( lp - 1 ) / 3 ) * 6 , 1 ) ) ) select s from x where ind = 0 /
This string can be transformed back to a nice display of the solution.
Solved in 1 Sec!….
My personal note: Sudoku is meant for human minds and not to be solved by a program. Hence you should enjoy solving them with your own minds. However you can use this if you are frozen at some point , unable to proceed further and frustration is about to begin…:)
Have a nice day!