Brute-force solution for hard-to-solve grids

For example:

	0, 3, 0, 0, 0, 6, 0, 1, 5,
	6, 0, 9, 1, 0, 2, 0, 0, 0,
	0, 0, 0, 0, 0, 8, 6, 0, 3,
	8, 0, 0, 0, 0, 0, 3, 6, 7,
	7, 0, 0, 0, 0, 0, 0, 0, 0,
	9, 2, 6, 0, 0, 0, 0, 0, 4,
	0, 9, 0, 0, 2, 0, 0, 0, 0,
	3, 0, 2, 0, 0, 7, 0, 4, 0,
	0, 0, 7, 6, 0, 1, 0, 3, 2