This is driving me crazy. For the last week, they have been putting these puzzles in the paper. I got bored with them pretty quickly (after solving one or two), but I thought it would be good programming practice to write a program to solve the puzzles. So that’s what I spent my day doing. My program has successfully solved (in under a second) all of the puzzles that I tested it with, except this one which was in the Sunday paper this morning.
I am convinced that, using logic alone, you can’t come to a solution. You’d have to guess after figuring out 49 of the boxes.
If any of you are into this kind of thing (or have a little time to kill), here are the rules (the puzzle is posted below).
You must use the numbers 1-9 only.
Each digit is used only once in each row, column, and 3x3 box.
The 3x3 boxes are arranged as follows:
xxx xxx xxx
xxx xxx xxx
xxx xxx xxx
xxx xxx xxx
xxx xxx xxx
xxx xxx xxx
xxx xxx xxx
xxx xxx xxx
xxx xxx xxx
Here’s the puzzle that’s driving me crazy:
x7x xxx 2x9
xxx 57x x61
xxx xx9 x3x
xx2 85x 7xx
7xx xxx xx4
xx1 x67 9xx
x5x 6xx xxx
98x x45 xxx
2x4 xxx x5x
If anybody wants, I can show you the dead end that I (and my program) hit. There are 49 boxes filled out of the 81 when I hit the dead end.
(The paper says this puzzle is “Black Belt” difficulty - the hardest of the three levels, so if anyone is interested in starting out, but not tackling a tough one yet, google sudoku, there will be tons of matches)