Puzzle

Puzzle 5 (Evil)

Non-Heuristic

Heuristic

	1	7		4	2
			9				6
	6			7
5			3				1	6
		3				5
1	7				6			8
				6			9
	2				4
			8	3		6	5

Sudoku may have been solved, does not display results.

[3,8,9]	1	7	6	4	2	[3,8,9]	[3,8]	5
[2,3,4,8]	[3,4,5,8]	[4,5,8]	9	[1,5,8]	[1,3,5,8]	[1,2,3,4,7,8]	6	[1,3,4,7]
[2,3,4,8,9]	6	[4,5,8,9]	[1,5]	7	[1,3,5,8]	[1,2,3,4,8,9]	[2,3,4,8]	[1,3,4,9]
5	[4,8,9]	[2,4,8,9]	3	[2,8,9]	[7,8,9]	[2,4,7,9]	1	6
6	[4,8,9]	3	[1,4,7]	[1,2,8,9]	[1,7,8,9]	5	[2,4,7]	[4,7,9]
1	7	[2,4,9]	[4,5]	[2,5,9]	6	[2,3,4,9]	[2,3,4]	8
[3,7,8]	[3,5,8]	[1,5,8]	2	6	[1,7]	[1,3,4,7,8]	9	[1,3,4,7]
[3,7,8,9]	2	6	[1,5,7]	[1,5,9]	4	[1,3,7,8]	[3,7,8]	[1,3,7]
[4,7,9]	[4,9]	[1,4,9]	8	3	[1,7,9]	6	5	2

applied square rule

applied triples rule

true ?

(435 ms) yes

Sudoku is solved using lots of backtracking.

9 1 7 6 4 2 3 8 5

2 3 4 9 8 5 1 6 7

8 6 5 1 7 3 2 4 9

5 4 9 3 2 8 7 1 6

6 8 3 7 1 9 5 2 4

1 7 2 4 5 6 9 3 8

7 5 8 2 6 1 4 9 3

3 2 6 5 9 4 8 7 1

4 9 1 8 3 7 6 5 2

The rules that would be necessary to deduce the puzzle from this state are beyond the scope of the rules in the non-heuristic approach. This explains why the heuristic problem had 413 lines worth of backtracking.