Sudoku-Solver

This Sudoku solver project uses python and the backtracking algorithm to find a solution to any solvable Sudoku board.

It includes two python programs

   - Graphical GUI 	  
   - Text based version.

(1) For GUI :-

(1) For this GUI to work it must be inside the same directory as the file called GUI_solver.py 

(2) You must also have pygame installed on your system.
	- Either import pygame package in your PyCharm IDE 
	- Or If want to run above code directly using python in cmd.
	- Run below command in cmd if pygame not installed.
	- "py -m pip install -U pygame --user"

(3) After installation of pygame run GUI.py to play Sudoku.

Instructions for Sudoku-GUI-Solver

- Click a box and hit the number on your keyboard to insert a number in that particular box.
- To confirm that value press the ENTER key on that box. 
- To delete the inserted number in a particular box, select it and click DEL on keyboard.
- Finally, if you want to solve the Sudoku board automatically press SPACE, sit back and watch the algorithm run.

(2) For Text based version :-

Run Sudoku-Text-Solver.py

About Backtracking

Backtracking is simply reverting back to the previous step or solution as soon as we determine that our current solution cannot be continued into a complete one.

We will use this principle of backtracking to implement our algorithm.

Algorithm

Starting with an incomplete board:

Find some empty space
Attempt to place the digits 1-9 in that space
Check if that digit is valid in the current spot based on the current board.

If the digit is valid, recursively attempt to fill the board using steps 1-3.

If it is not valid, reset the square you just filled and go back to the previous step.

Once the board is full by the definition of this algorithm we have found a solution.