To run the original 2006 application, download the JNLP file.
To run the 2014 verion that solves samurai sudoku puzzle, download this JNLP file.
You must have Java Web Start installed to run this file.
Click on a box and select a number from the pull-down to assign a number to a box. Grayed-out values are not allowed by the rules. Select "?" to reset the cell. Note that it may be reassigned right back to the same values by the rules, if the square is very constrained.
File->New to start over again.
Options->Freedom to get the colorful display of the number of options per cell: red is 9, purple is 1, black is 0.
Options->Solution to enable the background search that generates the "There are N solutions" messages in the status window.
Options->Diagonal to enable to great-diagonal constraint in addition to the typical row, column, and block constraints.
Options->Pick a Solution Causes the "Solve" Tool to return the first solution it finds, even if there are many solutions.
Tools->Solve Search for solutions and set the state of the board to a solution if and only one exists (or the first one if "Pick a Solution" is set.
File->Load loads the puzzle state from a file like this.
Turns out that the first version of the software had a bug that resulted in one of the six puzzles generating two apparent solutions: a correct one and an incorrect one. That's better than two incorrect solutions, eh? That bug has been fixed in this version.
I won! Although it wasn't really a fair head-to-head race. We each just worked on our parts when we felt like it. I may have won only because she didn't sit down and race through them. The original version was written in C++ and was less than about 300 lines of pretty not-dense code. That first version could solve the six puzzles in far less than a second on my laptop.
This version is a port to Java with a flashy little UI on it. The fact that the solver is so fast got me interested in the idea of creating some automated tools for authoring the puzzles.
I've also become interested in the structure of the puzzles: what makes them easy or hard. The colorful visualization in this venison is a step in that direction of inquiry.