Leetcode: Valid Sudoku

Question

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 ‘.’.

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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Analysis

check every row, col and 3×3 grids.

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Solution

class Solution:    # @param {character[][]} board    # @return {boolean}    def isValidSudoku(self, board):        n = len(board)        for row in range(n/3):            for col in range(n/3):                array = []                temp = board[row*3:row*3+3]                for i in range(3):                    array += temp[i][col*3:col*3+3]                if not self.helper(array):                    return False        for row in range(n):            if not self.helper(board[row]):                return False        for col in range(n):            array = []            for row in range(n):                array += [ board[row][col] ]            if not self.helper(array):                return False        return True    def helper(self, array):        dict = {}        for val in array:            if val!='.':                if val in dict:                    return False                else:                    dict[val] = val        return True