[Leetcode][Python]36: Valid Sudoku

# -*- coding: utf8 -*-‘‘‘__author__ = ‘[email protected]‘

36: Valid Sudokuhttps://oj.leetcode.com/problems/valid-sudoku/

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 ‘.‘.

Note:A valid Sudoku board (partially filled) is not necessarily solvable. Only the filled cells need to be validated.

===Comments by Dabay===先检查每个3x3的格子。然后遍历board，当遇到数字时，检查其所在的行和列。这里用d_row和d_col记录检查过的行和列，避免重复检查。‘‘‘

class Solution:    # @param board, a 9x9 2D array    # @return a boolean    def isValidSudoku(self, board):        for i in xrange(0, 9, 3):            for j in xrange(0, 9, 3):                d = {}                for x in xrange(i, i+3):                    for y in xrange(j, j+3):                        if board[x][y] == ‘.‘:                            continue                        n = board[x][y]                        if n in d:                            return False                        d[n] = True

        d_row = {}        d_col = {}        for i in xrange(0, 9):            for j in xrange(0, 9):                if board[i][j] == ‘.‘:                    continue                num = board[i][j]                if i not in d_row:                    d = {}                    for x in xrange(0, 9):                        if board[i][x] == ‘.‘:                            continue                        n = board[i][x]                        if n in d:                            return False                        d[n] = True                    d_row[i] = True                if j not in d_col:                    d = {}                    for y in xrange(0, 9):                        if board[y][j] == ‘.‘:                            continue                        n = board[y][j]                        if n in d:                            return False                        d[n] = True                    d_col[j] = True        return True

def main():    sol = Solution()    board = [        "53..7....",        "6..195...",        ".98....6.",        "8...6...3",        "4..8.3..1",        "7...2...6",        ".6....28.",        "...419..5",        "....8..79"    ]    print sol.isValidSudoku(board)

if __name__ == ‘__main__‘:    import time    start = time.clock()    main()    print "%s sec" % (time.clock() - start)