1 import java.util.Scanner;
2
3 public class CheckSudokuSolution {
4 public static void main(String[] args) {
5
6 int[][] grid = readASolution();
7
8 System.out.println(isValid(grid) ? "Valid solution"
9 : "Invalid solution");
10 }
11
12
13 public static int[][] readASolution() {
14
15 Scanner input = new Scanner(System.in);
16
17 System.out.println("Enter a Sudoku puzzle solution:");
18 int[][] grid = new int[9][9];
19 for (int i = 0; i < 9; i++)
20 for (int j = 0; j < 9; j++)
21 grid[i][j] = input.nextInt();
22
23 return grid;
24 }
25
26
27 public static boolean isValid(int[][] grid) {
28 for (int i = 0; i < 9; i++)
29 for (int j = 0; j < 9; j++)
30 if (grid[i][j] < 1 || grid[i][j] > 9
31 || !isValid(i, j, grid))
32 return false;
33 return true;
34 }
35
36
37 public static boolean isValid(int i, int j, int[][] grid) {
38
39 for (int column = 0; column < 9; column++)
40 if (column != j && grid[i][column] == grid[i][j])
41 return false;
42
43
44 for (int row = 0; row < 9; row++)
45 if (row != i && grid[row][j] == grid[i][j])
46 return false;
47
48
49 for (int row = (i / 3) * 3; row < (i / 3) * 3 + 3; row++)
50 for (int col = (j / 3) * 3; col < (j / 3) * 3 + 3; col++)
51 if (!(row == i && col == j) && grid[row][col] == grid[i][j])
52 return false;
53
54 return true;
55 }
56 }