Nick70 wrote:dukuso wrote:The relative hardness of Gordon's 17s was confirmed by Merri and others. Have you tested the whole list ?

I've run it through my solver. Here are the results:

- Code: Select all
`9276 diff 00 [trivial]`

5994 diff 01 [single unit candidate]

778 diff 02 [naked pair]

511 diff 03 [hidden pair]

4 diff 04 [x-wing]

1037 diff 05 [turbot fish]

17 diff 06 [naked triplet]

2 diff 07 [swordfish]

8 diff 08 [hidden triplet]

499 diff 09 [xy-wing]

61 diff 10 [skewed swordfish]

2 diff 14 [jellyfish]

931 diff 15 [forcing chain]

72 diff 16 [multi forcing chain]

5 diff 20 [guessing]

So as you can see more than three quarters of them are trivial or very easy.

thanks for the statistics !

Now, how does this compare with a sample of random sudokus ?

See also :

http://www.icparc.ic.ac.uk/~hs/sudoku.pdf

he has an updated version with tests on 7611 of Gordon's

and my top100, which I can send