From 0cfd960edb3bdde2ab117166029ac4e03e32144e Mon Sep 17 00:00:00 2001
From: Prerna Jha <114309444+Jprerna04@users.noreply.github.com>
Date: Tue, 29 Oct 2024 00:39:59 +0530
Subject: [PATCH] Create SudokuGame.java

This Java program solves a 9x9 Sudoku puzzle using the backtracking algorithm. The solveBoard() method recursively tries numbers in empty cells, backtracking if a number placement violates Sudoku rules, as checked by isValidPlacement(). Once solved, printBoard() displays the completed puzzle in an organized format.
---
 JavaProjects/SudokuGame.java | 78 ++++++++++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)
 create mode 100644 JavaProjects/SudokuGame.java

diff --git a/JavaProjects/SudokuGame.java b/JavaProjects/SudokuGame.java
new file mode 100644
index 0000000..d01aefb
--- /dev/null
+++ b/JavaProjects/SudokuGame.java
@@ -0,0 +1,78 @@
+public class SudokuSolver {
+    private static final int GRID_SIZE = 9;
+
+    public static void main(String[] args) {
+        int[][] board = {
+            {7, 0, 2, 0, 5, 0, 6, 0, 0},
+            {0, 0, 0, 0, 0, 3, 0, 0, 0},
+            {1, 0, 0, 0, 0, 9, 5, 0, 0},
+            {8, 0, 0, 0, 0, 0, 0, 9, 0},
+            {0, 4, 3, 0, 0, 0, 7, 5, 0},
+            {0, 9, 0, 0, 0, 0, 0, 0, 8},
+            {0, 0, 9, 7, 0, 0, 0, 0, 5},
+            {0, 0, 0, 2, 0, 0, 0, 0, 0},
+            {0, 0, 7, 0, 4, 0, 2, 0, 3}
+        };
+
+        if (solveBoard(board)) {
+            System.out.println("Sudoku solved successfully:");
+            printBoard(board);
+        } else {
+            System.out.println("Unable to solve Sudoku.");
+        }
+    }
+
+    private static boolean solveBoard(int[][] board) {
+        for (int row = 0; row < GRID_SIZE; row++) {
+            for (int col = 0; col < GRID_SIZE; col++) {
+                if (board[row][col] == 0) {  
+                    for (int num = 1; num <= GRID_SIZE; num++) {
+                        if (isValidPlacement(board, num, row, col)) {
+                            board[row][col] = num;
+
+                            if (solveBoard(board)) {
+                                return true;
+                            } else {
+                                board[row][col] = 0; 
+                            }
+                        }
+                    }
+                    return false; 
+                }
+            }
+        }
+        return true; 
+    }
+
+    private static boolean isValidPlacement(int[][] board, int number, int row, int col) {
+        for (int i = 0; i < GRID_SIZE; i++) {
+            if (board[row][i] == number || board[i][col] == number) {
+                return false;
+            }
+        }
+
+        int subgridRowStart = (row / 3) * 3;
+        int subgridColStart = (col / 3) * 3;
+        for (int i = 0; i < 3; i++) {
+            for (int j = 0; j < 3; j++) {
+                if (board[subgridRowStart + i][subgridColStart + j] == number) {
+                    return false;
+                }
+            }
+        }
+        return true;
+    }
+
+    private static void printBoard(int[][] board) {
+        for (int row = 0; row < GRID_SIZE; row++) {
+            if (row % 3 == 0 && row != 0) {
+                System.out.println("-----------");
+            }
+            for (int col = 0; col < GRID_SIZE; col++) {
+                if (col % 3 == 0 && col != 0) System.out.print("|");
+                System.out.print(board[row][col] == 0 ? "." : board[row][col]);
+            }
+            System.out.println();
+        }
+    }
+}