Puzzle

Puzzle 9 (Evil)

Non-Heuristic

Heuristic

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

Sudoku may have been solved, does not display results.

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

applied square rule

applied triples rule

true ?

(422 ms) yes

Sudoku is solved using backtracking.

7 3 8 1 4 2 6 5 9

5 4 1 9 3 6 7 2 8

2 6 9 5 8 7 3 4 1

4 9 7 8 6 1 5 3 2

3 1 5 7 2 9 4 8 6

6 8 2 3 5 4 9 1 7

9 7 3 2 1 5 8 6 4

8 2 6 4 9 3 1 7 5

1 5 4 6 7 8 2 9 3

In this instance the non-heuristic program fails to apply the doubles rule for the highlighted boxes. For example, the rules had been applied the remaining 7's and 9's in row 7 would have been removed.