FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in          Games  Calendar Log in to check your private messages    Box number          Sudoku Programmers Forum Index -> Programming sudoku View previous topic :: View next topic   Author Message ChPicard Joined: 12 Mar 2008 Posts: 82 : Location: Montreal, Canada Items Posted: Tue Sep 08, 2009 6:10 pm    Post subject: Box number HI What is the formula to calculate the box number (b=1; b<10;) from the given's position (x=0; x<81;)? Thank you Back to top humble_programmer Joined: 27 Jun 2006 Posts: 69 : Location: Colorado Springs, USA Items Posted: Tue Sep 08, 2009 9:20 pm    Post subject: Try this, where index is the square index in the range [0..80] Code: iBox = ((( index / 9) / 3) * 3) +  (( index % 9) / 3); The result in iBox will be in the range [0..8], so you may have to add 1; also, don't simplify the algebra, as it relies on the truncation of integers. _________________ Cheers! Humble Programmer ,,,^..^,,, www.humble-programmer.com Back to top Lunatic Joined: 11 Mar 2007 Posts: 166 : Location: Ghent - Belgium Items Posted: Wed Sep 09, 2009 3:06 pm    Post subject: humble_programmer wrote: Try this, where index is the square index in the range [0..80] Code: iBox = ((( index / 9) / 3) * 3) +  (( index % 9) / 3); The result in iBox will be in the range [0..8], so you may have to add 1; also, don't simplify the algebra, as it relies on the truncation of integers. However, you can simplify it... Code: iBox = (( index / 27) * 3) +  (( index % 9) / 3); In my program i use some global arrays, and the one for this purpose is called iCell2Box[0 to 80] Initiation at program start: Code: For (i=0;i<81;i++) iCell2Box(i) = ((i / 27) * 3) + ((i % 9) / 3); Wherever you want to know in which box a cell (index) is in, just use: Code: iBox = iCell2Box[index]; _________________ Marc ~~~<><~~~<><~~~<><~~~<><~~~ Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         Sudoku Programmers Forum Index -> Programming sudoku All times are GMT Page 1 of 1   Jump to: Select a forum Sudoku----------------Solving sudokuSetting sudokuProgramming sudokuThe mathematics of sudokuExotic sudoku Library----------------PuzzlesSoftwareSudoku elsewhere Not sudoku----------------Random thoughtsForum feedback  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum   Powered by phpBB © 2001, 2005 phpBB Group Igloo Theme Version 1.0 :: Created By: Andrew Charron