Sudoku (pronounced soo-dough-coo with the emphasis on the first syllable) is a simple number-based puzzle/game played on a 9x9 grid that is divided into 3x3 subgrids. The goal is to enter a number from 1 to 9 in each cell so that each number appears only once in each column and row. In addition, each 3x3 subgrid may only contain one of each number.
This version of the puzzle is Copyright 2005 by Michael R Sweet
Reference: http://www.easysw.com/~mike/sudoku/index.html
