Friday 4 November 2011

Friday Puzzles #129

So this is my last entry before I jet off to Hungary to have a shot at firstly the World Sudoku Championship, and then the World Puzzle Championship next week. I’ll be travelling with laptop and notebook so there might even be a puzzle next week. I invite you, dearest of readers, to be on the lookout for updates here throughout the week.

For those that are interested, the instruction booklets for each competition are filled with some intriguing ideas.

This week’s puzzle has been taken from the WSC booklet. The only previous examples of these that I’ve seen have been no larger than 7×7 grids, but I’ve whacked this up to full size. The rules are as follows: 1-9 exactly once in each row, column and marked region. Some squares are split in half; exactly one half is to be filled, the other to be left empty. You have to determine which. I’m not totally convinced this is genuinely a hard, but I’ll give it that label anyway what with the novelty value. Enjoy!
    #159 Halved Squares Sudoku – rated hard
All puzzles © Tom Collyer 2009-11


  1. Errrr, column 3 ?!

  2. whoops, that 1 should be a 5, let me fix it…

  3. Made me feel crazy !!!

    At the 5th tentative, it was correct !

    Thanks for the grid.


  4. The idea Fred was to try and put something more horrible than will appear in Eger. Hopefully this will prove to be the case!

  5. Yeah, it’s an interesting observation. Initially I had wanted to put no givens in the halved cells – if nothing else the formatting looks a bit rubbish – but I couldn’t get anything unique out. Perhaps this is a limitation to the variant in larger sizes, but I’m not totally convinced we’ll see many in a 9×9 size anyway…

  6. Good workout.

    Have you seen any similar puzzles with all regions convex? I’ve made a 7×7 grid with that property, but I haven’t figured out how to fill it.


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