36. 有效的数独 Valid Sudoku

Determine if a 9 x 9 Sudoku board is valid. Only the filled cells need to be validated according to the following rules:

1. Each row must contain the digits 1-9 without repetition.
2. Each column must contain the digits 1-9 without repetition.
3. Each of the nine 3 x 3 sub-boxes of the grid must contain the digits 1-9 without repetition.

Note:

• A Sudoku board (partially filled) could be valid but is not necessarily solvable.
• Only the filled cells need to be validated according to the mentioned rules.

方法：

遍历9*9的二维矩阵即可，将出现的数据放在map里

 

public boolean isValidSudoku(char[][] board) {
        Map<Integer,Map<Character,Integer>> rows = new HashMap<>();
        Map<Integer,Map<Character,Integer>> cols = new HashMap<>();
        Map<Integer,Map<Character,Integer>> block = new HashMap<>();
        for (int i = 0; i < 9; i++){
            Map<Character,Integer> rowMap= new HashMap<>();
            rows.put(i,rowMap);
            Map<Character,Integer> colMap= new HashMap<>();
            cols.put(i,colMap);
            Map<Character,Integer> blockMap= new HashMap<>();
            block.put(i,blockMap);
        }
        for (int i =0 ;i < 9; i++){
            for(int j = 0; j < 9; j++){
                if (board[i][j] == '.') continue;
                if (rows.get(i).containsKey(board[i][j])) return false;
                else rows.get(i).put(board[i][j],1);
                if (cols.get(j).containsKey(board[i][j])) return false;
                else cols.get(j).put(board[i][j],1);
                if(block.get(i/3*3+j/3).containsKey(board[i][j])) return false;
                else block.get(i/3*3+j/3).put(board[i][j],1);
            }
        }

        return true;
    }

 

参考链接：

https://leetcode.com/problems/valid-sudoku/

https://leetcode-cn.com/problems/valid-sudoku/