36. Valid Sudoku （判断数独）

悠悠 2022-07-15 01:16 166阅读 0赞

Determine if a Sudoku is valid, according to: [Sudoku Puzzles - The Rules][].

The Sudoku board could be partially filled, where empty cells are filled with the character `'.'`.

![250px-Sudoku-by-L2G-20050714.svg.png][]

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.

import java.util.Hashtable;
    public class Solution {
        public boolean isValidSudoku(char[][] board) {
    		Map<Character, Integer> table = new Hashtable<Character, Integer>();
    		for (int i = 0; i < 9; i++) {
    			for (int j = 0; j < 9; j++) {
    				if (table.get(board[i][j]) == null)
    					table.put(board[i][j], 1);
    				else if (board[i][j] != '.')
    					return false;
    			}
    			table.clear();
    		}
    		for (int i = 0; i < 9; i++) {
    			for (int j = 0; j < 9; j++) {
    				if (table.get(board[j][i]) == null)
    					table.put(board[j][i], 1);
    				else if (board[j][i] != '.')
    					return false;
    			}
    			table.clear();
    		}
    		for (int i = 0; i < 9; i++) {
    			for (int j = 0; j < 9; j++) {
    				if (table.get(board[i][j]) == null)
    					table.put(board[i][j], 1);
    				else if (board[i][j] != '.')
    					return false;
    			}
    			table.clear();
    		}
    		for (int x = 0; x < 7; x += 3)
    			for (int y = 0; y < 7; y += 3) {
    				for (int i = x; i < x + 3; i++) {
    					for (int j = y; j < y + 3; j++) {
    						if (table.get(board[i][j]) == null)
    							table.put(board[i][j], 1);
    						else if (board[i][j] != '.')
    							return false;
    					}
    				}
    				table.clear();
    			}
    		return true;
    	}
    }

[Sudoku Puzzles - The Rules]: http://sudoku.com.au/TheRules.aspx
[250px-Sudoku-by-L2G-20050714.svg.png]: /images/20220715/dece3565a5134f12957e297daaba210b.png