Sudoku Solver

This Java code defines a program for solving Sudoku puzzles. Sudoku is a logic-based number placement puzzle, where the goal is to fill a 9x9 grid with digits so that each column, each row, and each of the nine 3x3 subgrids (also known as regions or boxes) contain all of the digits from 1 to 9 without repetition.

Here's a breakdown of the code's main components and functionality:

1. display method:

   • This method is responsible for displaying the current state of the Sudoku board.
   • It uses ANSI escape codes for terminal text coloration to make the output visually appealing.
   • It prints the Sudoku board, with each cell's value in either cyan or yellow color, separated by vertical and horizontal lines.

2. solve method:

   • This is the main recursive method that attempts to solve the Sudoku puzzle.
   • It takes the current Sudoku board, row (i), and column (j) as parameters.
   • The method progresses through the grid, trying to fill in valid numbers (1-9) in empty cells.
   • If it successfully fills in the entire board, it prints the solution.
   • If the board cannot be solved, it backtracks by resetting a cell's value to 0 and continues exploring other possibilities.

3. isValid method:

   • This method checks whether it's valid to place a number (val) in a specific cell (x, y) of the Sudoku board.
   • It checks three conditions: row, column, and subgrid (3x3 box). If the number already exists in any of these conditions, it returns false; otherwise, it returns true.

4. main method:

   • The main method is the entry point of the program.
   • It initializes a 9x9 Sudoku board with a starting configuration. The provided example is a typical Sudoku puzzle.
   • Alternatively, you can uncomment a section of code to input the Sudoku puzzle from the console using a Scanner.
   • It displays the initial state of the Sudoku board and then calls the solve method to find a solution.
   • If a solution is found, it is printed. Otherwise, it prints "No solution possible" if no valid solution exists.

Overall, this code provides a Sudoku solver that uses a recursive backtracking algorithm to find the solution to the puzzle. It is capable of solving most standard Sudoku puzzles and provides a visual representation of the solved board using colored text.