Valid Sudoku
Determine if a Sudoku is valid, according to: Sudoku puzzles-the rules.
The sudoku board cocould be partially filled, where empty cells are filled with the character‘.‘
.
A partially filled Sudoku which is valid.
Note:
A valid Sudoku Board (partially filled) is not necessarily solvable. Only the filled cells need to be validated.
Algorithm ideas:
Determine whether a row or column conflict exists one by one, and then determine one by one.
I can see a matrix mark written by danale on the Internet. I can see it again. Do not dare to shift the door, and then upload the algorithms of others.
The Code is as follows:
1 public class Solution { 2 public boolean isValidSudoku(char[][] board) { 3 if(board == null || board.length != 9 || board[0].length != 9) return false; 4 boolean[][] row = new boolean[9][9]; 5 boolean[][] col = new boolean[9][9]; 6 boolean[][] matrix = new boolean[9][9]; 7 for(int i = 0; i < 9; i++){ 8 for(int j = 0; j < 9; j++){ 9 if(board[i][j] == ‘.‘) continue;10 int n = board[i][j] - ‘1‘;11 if(row[i][n] || col[j][n] || matrix[i - i % 3 + j / 3][n]){12 return false;13 }14 row[i][n] = col[j][n] = matrix[i - i % 3 + j / 3][n] = true;15 16 }17 }18 return true;19 }20 }