Sudoku Solver Comparison

1. Sudoku Solver Comparison A comparative analysis of algorithms for solving Sudoku

2. What is a Sudoku Puzzle? • A pencil-and-paper puzzle, much like a numeric crossword puzzle • A special type of latin square • Seen in many newspapers, including our own K-State Collegian • A highly-connected CSP • Typical 9 x 9 configuration • 81 variables, each constrained by 24 other variables • Total of 972 constraints • A valid solution is a 9-coloring of the constraint graph

3. Sudoku Rules • Common Sudoku puzzles are a 9 x 9 grid of 81 cells • There are 9 rows and 9 columns • Also divided into 9 3 x3 boxes • Each cell can hold one number, an integer between 1 and 9, inclusive • Some subset of the cells are given • Each number can only appear once in each row, column, and box • Valid Sudoku have enough cells given that there is a unique solution

4. Sudoku images Solved Given

5. Algorithms • General constraint satisfaction algorithms • Backtracking search • A “brute force” approach • Serves as the baseline • Backtracking with MRV • Look for values that are the “most constrained” in the current state • Sudoku specific algorithms • Human-like approach • Avoid guessing (and backtracking!) • Some additional constraints can be deduced from values of non-adjacent cells