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

思路

本题是判断目前九宫给填上的数字是否有效

即：行无重复，列无重复，所在的小九宫格中无重复

所在第几个九宫格：$i/3*3+j/3$

class Solution(object):    def isValidSudoku(self,board):        doc={}        doc_rows={}        for i in range(9):            for j in range(9):                if board[i][j]!='.':                    if (board[i].count(board[i][j])>1):                        return False                    doc_rows.setdefault(j,[])                    if board[i][j] not in doc_rows[j]:                        doc_rows[j].append(board[i][j])                    else:                        return False                    doc.setdefault(i/3*3+j/3,[])                    if board[i][j] not in doc[i/3*3+j/3]:                        doc[i/3*3+j/3].append(board[i][j])                    else:                        return False        return TrueS=Solution()board=[[5,3,'.','.',7,'.','.','.','.'],       [6,'.','.',1,9,5,'.','.','.'],       ['.',9,8,'.','.','.','.',6,'.'],       [8,'.','.','.',6,'.','.','.',4],       [4,'.','.',8,'.',3,'.','.',1],       [7,'.','.','.',2,'.','.','.',6],       ['.',6,'.','.','.','.',2,8,'.'],       ['.','.','.',4,1,9,'.','.',5],       ['.','.','.','.',8,'.','.',5,9]]print S.isValidSudoku(board)

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