Valid Sudoku

The Sudoku board could 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.

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[分析]

每行,每列,每个square,都不能重复.用 SET 记录即可. 

[CODE]

class Solution(object):
    def isValidSudoku(self, board):
        """
        :type board: List[List[str]]
        :rtype: bool
        """
        row,col,square = [],[],[]
        for i in range(10):
            row.append(set())
            col.append(set())
            square.append(set())
            
        
        for i in range(len(board)):
            for j in range(len(board)):
                n = board[i][j]
                if n=='.':continue
                elif n<'0' or n>'9':return False
                elif n in row[i] or n in col[j] or n in square[i/3*3+j/3]:
                    return False
                else:
                    row[i].add(n)
                    col[j].add(n)
                    square[i/3*3+j/3].add(n)
        return True