Posted on

## Sudoku Y

Sudoku X has been an alternative to regular Sudoku puzzles, when I wanted some minimal relief. Having a vest pocket pair of constraints when I was otherwise reduced to guessing was nice. The site: easton.me.uk provides a downloadable (Windows) Puzzle Generator for Sudoku X (Nothing on this variant, though).

Because this variation is not one that Sudoku Solvers solve programmatically, I had to reverse engineer the solution by specifying a proper set of values for the Y and then solving by adding one number at a time and insuring that the result did not produce a conflict with the other cells. I stopped when there was a single unique solution. (I used the Web Based: Sudoku Solver By Logic.) I’m not sure if I could have provided fewer clues, but feel free to erase as many as you want and see if you can solve it that way.

Posted on

## Sudoku Wraps

This Sudoku variant offers the ability of Blocks of 9 to be non-contiguous as well as non-square on the grid. Other versions of this kind of puzzle do not offer the gift of colorization, but merely the outline of the misshapen blocks. This is reminiscent of the Jigsaw Sudoku Puzzle Cartoon of a month ago, which also offered non-square block shapes, but were contiguous. These variants have also been known as Geometric (or Latin Square) Sudoku by Ed Pegg writing for the Mathematical Association of America.

Posted on

## Subset Sudoku

This Sudoku variant supplies the correct triad locations of the numbers of the solved puzzle, but offers far fewer starting numbers. Even so, the puzzle is solvable when considering the subset of candidates that can be in a particular cell.

I found a math site called cut-the-knot.org that shows how you can intersperse only plus or minus signs to the fixed sequence of digits 1 2 3 4 5 6 7 8 9 so that the resulting arithmetic expression, when simplified, is 100. It’s both harder and easier than you think! Likewise, the sequence 9 8 7 6 5 4 3 2 1 is also considered for expressions results simplifying to 100.  There’s more than one, but not many.

Posted on

## Odd Sudoku

I had to skip a week due to superceding short term tasks to complete involving a Linux workshop I conducted last week.

This Sudoku variant supplies the correct odd/even location of the numbers of the solved puzzle, but offers fewer starting numbers. This encourages constraining logic when considering the possibilities of each cell.

A discussion of Odd and Even Numbers is offered in Wikipedia.

Posted on

## Battleship Sudoku

Two games in one: Battleship and Sudoku. There are fewer Sudoku clues and added Battleship clues. Use both sources to solve both objectives. The battleships in the fleet are either horizontal or vertical and are totally non-adjacent to each other. The border numbers show the number of cells in a row or column that are contained on one or more battleships.

This variant stems from the 2007 Sudoku Championship Puzzle Instruction Book (in pdf format)

Posted on

## Sudoku Puzzle Creation

When your spiffy Computerized, Programmatic Sudoku Puzzle Generator is not available, consider the low-technology, self-involving, self-sufficient random number generator and cell locator tools. You need at least 17 starting numbers and symmetry is required only for the obsessive compulsive (or Virgo people). Don’t start with too many numbers, though, unless creating unsolvable puzzles is your goal.