A 4x4 sudoku puzzle has 4 rows, 4 columns and 4 2x2 square regions, one in each corner. Can you create a 4x4 sudoku puzzle with only 4 clues given?

The most common sudoku variant is X-sudoku where the two main diagonals are two extra regions. Can you create a 4x4 X-sudoku puzzle with only 3 clues given?

If you start with

1 2 . .
. . . .
. . . .
. . . 3

you get an unique solution:

1 2 3 4
3 4 1 2
4 3 2 1
2 1 4 3  

Edited on March 19, 2007, 3:03 pm

Posted by Old Original Oskar! on 2007-03-19 15:02:05