Sudoku

My take on creating a Sudoku solver with Python

Install

Install this pacakge from the source:

$ git clone https://github.com/yonatank93/Sudoku.git
$ pip install Sudoku/

Example

In [1]: import json, sudoku

In [2]: data = json.load(open("Sudoku/data/board_01.json", "r"))

In [3]: board = sudoku.Board(data["board"])

In [4]: board.solve()
Solving time: 0:00:00.018726

In [5]: board.display()
#####################################
# 4 | 7 | 8 # 6 | 9 | 3 # 1 | 5 | 2 #
#-----------#-----------#-----------#
# 5 | 2 | 6 # 7 | 1 | 8 # 4 | 9 | 3 #
#-----------#-----------#-----------#
# 1 | 3 | 9 # 4 | 2 | 5 # 8 | 7 | 6 #
#####################################
# 3 | 8 | 5 # 1 | 4 | 7 # 6 | 2 | 9 #
#-----------#-----------#-----------#
# 7 | 4 | 2 # 9 | 8 | 6 # 5 | 3 | 1 #
#-----------#-----------#-----------#
# 6 | 9 | 1 # 5 | 3 | 2 # 7 | 4 | 8 #
#####################################
# 8 | 5 | 4 # 3 | 6 | 9 # 2 | 1 | 7 #
#-----------#-----------#-----------#
# 2 | 1 | 3 # 8 | 7 | 4 # 9 | 6 | 5 #
#-----------#-----------#-----------#
# 9 | 6 | 7 # 2 | 5 | 1 # 3 | 8 | 4 #
#####################################

In [6]:

Algorithm

1. For each empty tile, list possible values by only looking at the block, row, and collumn corresponding to that tile.
2. Try to solve the tile by only looking at the list of possible values for that tile. That is, if the list of possible values only contains one item, then that value must be for that tile.
3. Compare the list of possible values of tiles in the same block. If there is an item in the list of possible values of a tile that is not in the same kind of list for the other tiles, then that value can only be in that tile.
4. Do the same as step 3 for tiles in the same row and column.
5. Terminate if all tiles are filled.

Special case: If the empty tiles for before and after applying step 1-4 above are the same, then the algorithm above cannot proceed further. In this case, find the tile with least number of possible values and set that tile to one of the possible value. Then, continue with the algorithm above again.

Disclaimer

This algorithm works for all examples included with this repo! However, this is probably not the best algorithm for solving Sudoku.