Friday, 30 May 2014

Daily League Sudoku #42: Hit Sudoku

Last weekend was the Japanese NumberPlace Championship. It was full of great puzzles, but my favourite was the Hit NumberPlace by Naoki Inaba. I didn't manage to solve it during the championship as I didn't find the logic. But once I found the logic afterwards I really enjoyed it. That's why I decided to write one of my own for the league.

During the solve I realised a bit of logic that I thought would be fun to use in one of these puzzles. I just had to find a nice solution grid in which I could easily implement this. I actually stole a solution grid from the JNPC, which I slightly altered as at one point during construction I ran into no solution. But I noticed that by switching a few numbers around it could still have a solution. The trick I used isn't overly hard but I think it might be wise to try to solve the original puzzle first so that you can understand the logic involved, because I think it is useful to understand the genre before attempting this puzzle. The hit NumberPlace is #19 in the set.

That said, the puzzle is completely logically solvable. I think it is nice but it a bit on the harder side. Still, I hope you'll enjoy it.

Rules for Sudoku

Numbers outside the original grid indicate how many digits are the same in the solution grid in the corresponding row or column.

Click to enlarge


  1. Great sudoku, Bram!
    To be honest, I have not found the logical path, so I tried both possibilities for number 9 in 4th row. I guess that this is not the logical path you mention...


    1. The logical opening involves row4. A 6 clue only has two ways on how the wrong digits are reordered. So you know where either the 6 or the 9 in row 4 goes. What information does this give you about row 5? There's a bit more to be done with row 6 and row 9, but this was the logic I mentioned in the post.