###### March 16, 2009

# Scientist’s sudoku solution

A South Carolina computer scientist says he has come up with an infallible system for solving sudoku puzzles.

J.F. Crook, a computer scientist at Winthrop University, said in the latest Notices of the American Mathematical Society that he has come up with the first mathematically guaranteed system for solving the popular numbers puzzle, USA Today reported Monday.

Sudoku generally involves a grid of 81 squares, some of which contain numbers 1-9. The object is to fill in the remaining boxes with single-digits while avoiding repeating numbers in a row, column or the nine interior 3-by-3 boxes.The algorithm is a tree-based search algorithm based on backtracking in a tree until a solution is found,

Crook wrote in his paper, which was published Monday at ams.com.

Crook said the solution involves considering two possible numbers for each box and he recommends using different colors of pencils to keep track along the way.