Question

How to fill a 3x3 grid to be a valid Sudoku grid in Java

Answer 1

import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Random;

// To fill a 3x3 grid to be a valid Sudoku grid, you must ensure that each row, 
// column, and the 3x3 grid contains the numbers 1 through 9 without repetition.

public class SudokuGridGenerator {

    private static final int SIZE = 3;

    // Function to shuffle an array
    private static void shuffle(Integer[] array) {
        List<Integer> list = Arrays.asList(array);
        Collections.shuffle(list, new Random());
    }

    // Function to fill the Sudoku grid
    private static void fillSudokuGrid(int[][] grid) {
        Integer[] numbers = {1, 2, 3, 4, 5, 6, 7, 8, 9};

        // Shuffle the numbers randomly
        shuffle(numbers);

        // Fill the 3x3 grid row by row
        int index = 0;
        for (int i = 0; i < SIZE; i++) {
            for (int j = 0; j < SIZE; j++) {
                grid[i][j] = numbers[index++];
            }
        }
    }

    // Function to print the grid
    private static void printGrid(int[][] grid) {
        for (int i = 0; i < SIZE; i++) {
            for (int j = 0; j < SIZE; j++) {
                System.out.print(grid[i][j] + " ");
            }
            System.out.println();
        }
    }

    public static void main(String[] args) {
        // Initialize an empty 3x3 grid
        int[][] grid = new int[SIZE][SIZE];

        // Fill the grid with a valid Sudoku configuration
        fillSudokuGrid(grid);

        // Print the grid
        System.out.println("Generated 3x3 Sudoku Grid:");
        printGrid(grid);
    }
}


 
/*
run:
 
Generated 3x3 Sudoku Grid:
7 8 3 
9 5 2 
4 1 6 
 
*/

 

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