Sudoku Solver

Enter your puzzle and click Solve

 

Technical Features

1. 3x3 Subgrid Styling: The CSS uses the :nth-child selector to apply thicker borders every 3 cells and rows. This creates the visual "blocks" essential for reading Sudoku.

2. Input Filtering: The oninput JavaScript listener ensures that users can only type single digits (1-9). It prevents "0" and multi-digit numbers from breaking the logic.

3. Recursive Search: The solve() function is a depth-first search. It attempts a number and immediately moves to the next empty spot, only returning false (backtracking) if a placement becomes impossible.

4. Visual Feedback: Solved numbers are assigned a .solved class, which changes their color and triggers a subtle background animation so you can see what the AI filled in versus what you started with.