The Model and Algorithm to Estimate the Difficulty Levels of Sudoku Puzzles

Sudoku is a number placement mathematical puzzle based on logic. The purpose of this paper is to discuss suitable models and algorithm to generate Sudoku puzzles of varying difficulty. It is generally recognized that hand-made puzzles are more enjoyable than those generated by computer. Our goal is to establish models to generate Sudoku puzzles of varying difficulty, which are as enjoyable as hand-made ones. As we believe that puzzles generated by simulating the design process of hand-made ones will also be of much enjoyment, we established our first model -No Brute-Force. Brute-Force technique is excluded from this algorithm, for there is no enjoyment in solving puzzles using it. We have implemented the algorithm with a JAVA program. We conclude that it is possible and reasonable to generate Sudoku puzzles of varying difficulty as enjoyable as hand-made ones.