# Sudoku (Brain Teaser) **URL:** \ **Category:** random\ **Created:** [September 19, 2005, 12:01am UTC](https://forum.kirupa.com/t/sudoku-brain-teaser/163013 "2005-09-19T00:01:55Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![Yeldarb](https://avatars.discourse-cdn.com/v4/letter/y/51bf81/32.png) [@Yeldarb](https://forum.kirupa.com/u/Yeldarb)\ **Post date:** [September 19, 2005, 12:01am UTC](https://forum.kirupa.com/t/sudoku-brain-teaser/163013/1 "2005-09-19T00:01:55Z")
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: ```auto 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: ```auto 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)