Xaymar / js-sudoku

A simple 9x9 Sudoku generator using the Wave Function Collapse principles

Sudoku Generator in JavaScript

A generator for solvable Sudokus using Wave Function Collapse principles.

How do I build this?

npm install
npm run build

Usage

node . [N]

N is the number of fields that should remaing unsolved. A value of 0 solves the entire field.

How does it work?

The generator relies on the same principles behind Wave Function Collapse, though it was optimized according to the rules of Sudoku. With a little extra work it could even support abnormal cell groupings, as seen on harder ("impossible") Sudokus. As a step by step:

1. Generate 3*N Sets containing all possible numbers for a Row, Column and Group.
2. Generate an Array of N*N Cells and assign them a Set for Row, Column and Group generated in Step 1.
3. While we still have unsolved Cells:
   1. Randomize the Array of unsolved Cells fairly.
   2. Pick a Cell with the lowest available options.
   3. Collapse the chosen Cell.
   4. Remove the chosen Cell from the remaining unsolved Cells.
4. Done!

Known Problems

• Sometimes it needs more than one cycle to generate a field, which is most likely due to the naive collapse() function.
  • Perhaps this may be solvable with validated solving to ensure that the chosen value will not eliminate all possible solutions from another Row, Column or Group.