Create test.java

test.java

@@ -0,0 +1,106 @@
+public class SudokuSolver {
+    public static boolean solveSudoku(int[][] board) {
+        int N = board.length;
+
+        if (!isUnsolved(board)) {
+            return true; // The Sudoku is already solved
+        }
+
+        for (int row = 0; row < N; row++) {
+            for (int col = 0; col < N; col++) {
+                if (board[row][col] == 0) {
+                    for (int num = 1; num <= 9; num++) {
+                        if (isSafe(board, row, col, num)) {
+                            board[row][col] = num;
+                            if (solveSudoku(board)) {
+                                return true; // If this move leads to a solution, return true
+                            }
+                            board[row][col] = 0; // If not, reset and try the next number
+                        }
+                    }
+                    return false; // If no number is valid, return false
+                }
+            }
+        }
+        return false; // To handle unsolvable puzzles
+    }
+
+    public static boolean isSafe(int[][] board, int row, int col, int num) {
+        return !usedInRow(board, row, num) &&
+               !usedInCol(board, col, num) &&
+               !usedInBox(board, row - row % 3, col - col % 3, num);
+    }
+
+    public static boolean usedInRow(int[][] board, int row, int num) {
+        for (int col = 0; col < board.length; col++) {
+            if (board[row][col] == num) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    public static boolean usedInCol(int[][] board, int col, int num) {
+        for (int row = 0; row < board.length; row++) {
+            if (board[row][col] == num) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    public static boolean usedInBox(int[][] board, int boxStartRow, int boxStartCol, int num) {
+        for (int row = 0; row < 3; row++) {
+            for (int col = 0; col < 3; col++) {
+                if (board[row + boxStartRow][col + boxStartCol] == num) {
+                    return true;
+                }
+            }
+        }
+        return false;
+    }
+
+    public static boolean isUnsolved(int[][] board) {
+        int N = board.length;
+        for (int row = 0; row < N; row++) {
+            for (int col = 0; col < N; col++) {
+                if (board[row][col] == 0) {
+                    return true;
+                }
+            }
+        }
+        return false;
+    }
+
+    public static void printBoard(int[][] board) {
+        int N = board.length;
+        for (int r = 0; r < N; r++) {
+            for (int d = 0; d < N; d++) {
+                System.out.print(board[r][d]);
+                System.out.print(" ");
+            }
+            System.out.print("\n");
+        }
+    }
+
+    public static void main(String[] args) {
+        int[][] board = {
+            {5, 3, 0, 0, 7, 0, 0, 0, 0},
+            {6, 0, 0, 1, 9, 5, 0, 0, 0},
+            {0, 9, 8, 0, 0, 0, 0, 6, 0},
+            {8, 0, 0, 0, 6, 0, 0, 0, 3},
+            {4, 0, 0, 8, 0, 3, 0, 0, 1},
+            {7, 0, 0, 0, 2, 0, 0, 0, 6},
+            {0, 6, 0, 0, 0, 0, 2, 8, 0},
+            {0, 0, 0, 4, 1, 9, 0, 0, 5},
+            {0, 0, 0, 0, 8, 0, 0, 7, 9}
+        };
+
+        if (solveSudoku(board)) {
+            System.out.println("Sudoku Solved Successfully:");
+            printBoard(board);
+        } else {
+            System.out.println("No solution exists.");
+        }
+    }
+}