A Dataset of Sudoku Puzzles With Difficulty Metrics Experienced by Human Players

Sudoku is a popular logic-based puzzle game. Difficulty rating of a Sudoku puzzle is a difficult problem and a large number of research works have been proposed to tackle the problem. How to evaluate a difficulty rating algorithm is also a challenging problem. Different existing algorithms evaluate their effectiveness by using different datasets. Furthermore, some datasets are not based on the records played by human players. Therefore, the algorithms cannot be compared by using a standard dataset. In this paper, we construct a dataset of Sudoku puzzles with difficulty metrics experienced by human players. We first developed an Android application named Cloud Sudoku to collect the playing records. The development of Cloud Sudoku application has been briefly described in our previous work. This paper describes more details about database structures and features to collect the data. Two difficulty metrics are then proposed for each Sudoku puzzle based on the duration spent and the ratio which is successfully solved. A dataset of Sudoku puzzles with their difficulty metrics is designed and constructed. The difficulty metrics are shown to be close to the records played by human players. Therefore, the proposed dataset can be used to evaluate the difficulty rating algorithms. The dataset is now available on Github platform.