#WIKIPEDIA SUDOKU STRATEGY FREE#

Import itertools def separate_edges ( n ): G = nx. Informally the Sudoku graph is an undirected graph- its vertices represent the cells and edges represent pairs of cells that belong to the same row, column, or block of the puzzle. Here pre-coloring extension simply means translating the pre-existing cues into a graph with 81 nodes, coloring the nodes that are already given as clues, and then trying to color the rest of the vertices within the contraints.Ĭayley graph is simply a way of encoding information about group in a graph, as in we can define the sudoku puzzle completely in terms of a Graph, without missing any logical information or mathematical properties Problem Formulation # The problem of solving a Sudoku puzzle can be represented as precoloring extension on this graph. We may not get time to plant a tree, but we can definitely donate ₹42 per Tree.In the mathematics of Sudoku, the Sudoku graph is an undirected graph whose vertices represent the cells of a (blank) Sudoku puzzle and whose edges represent pairs of cells that belong to the same row, column, or block of the puzzle. If you like the content on CodePumpkin and if you wish to do something for the community and the planet Earth, you can donate to our campaign for planting more trees at CodePumpkin Cauvery Calling Campaign. You can also contribute your articles by creating contributor account here. We would be happy to add that in our post.

#WIKIPEDIA SUDOKU STRATEGY FREE#

If you guys have any suggestions or queries, feel free to drop a comment. you can also go through our other articles on different algorithms and data structures. You can also check the other articles on sorting and searching such as selection sort, binary search, fibonacci search, merge sort etc. This process continues until it finds correct solution or reach to the stage from where no solution can be found.ĭisplaySudoku() method is used to display 9×9 array in form of sudoku. But in case no other possible number remains, again it will bactrack to previously assigned cell and process continues. If it finds any allowed number, then it assigns this new number to cell and process continues again. If function returns false, control will backtrack to previously assigned cell and try for another number there. This process continues until it finds some cell for which no number is allowed and function will return false. It checks for allowed numbers from 1 to 9, assign the first possible option to cell and again call solveSudoku() method for next UNASSIGNED cell. It checks cells in each row one by one and picks up first cell with UNASSIGNED value. SolveSudoku() method starts traversing from top left cell to the right side. Return !(containsInRow(row, number) || containsInCol(col, number) || containsInBox(row, col, number)) Private boolean isAllowed(int row, int col,int number) If any of above three method return true, it means particular number is not allowed in that cell. IsAllowed() method uses above three methods to check if it is safe to assign number in the cell. Private boolean containsInBox(int row, int col,int number) Private boolean containsInCol(int col,int number) Private boolean containsInRow(int row,int number) private boolean containsInRow(int row,int number)īelow three methods are used to check, if number is present in current row, current column and current 3X3 subgrid or not. 0 value in any of its cell, is considered to be incomplete or wrong. Instance variable sudoku can be initialized using any of the below two constructors.Īll the cells of completely solved sudoku array must have assigned valid values.

Sudoku, 9×9 int array is used to store all the elements of sudoku. Approach for solving sudoku using recursive backtracking algorithm

Backtracking is also known as depth-first search. But backtrack to where? to the previous choice point. Think of a labyrinth or maze – how do you find a way from an entrance to an exit? Once you reach a dead end, you must backtrack. Briefly, once you exhaust all your options at a certain step you go back. If at some step it becomes clear that the current path that you are on cannot lead to a solution you go back to the previous step (backtrack) and choose a different path. In backtracking algorithms you try to build a solution one step at a time.

Sudoku can be solved using recursive backtracking algorithm. For other Backtracking algorithms, check my posts under section Backtracking (Recursion). If you are interested in java programs for other board games like Sudoku Checker, Tic Tac Toe, Snake N Lader and N Queen Problem , you can check out my posts in Board Games section. If you are looking for program to check correctness of Sudoku, you will find it in my post Sudoku checker (By traversing each cell only once). This post is about generating solution for sudoku problem and not for checking if solution is correct or not.

Wikipedia sudoku strategy