力扣36题 数独

import time
class Solution:
    def isValidSudoku(self, board):
        def isvalid(board, row, col, c):                                                    #操作是否合格
            for i in range(9):
                if board[i][col] != '.' and board[i][col] == c:  # row                      #判断这一行的数据
                    return False
                if board[row][i] != '.' and board[row][i] == c:  # col                      #判断这一列的数据
                    return False
                if (board[3 * (row // 3) + i // 3][3 * (col // 3) + i // 3] != '.') and (   #判断每个小隔间的3*3
                        board[3 * (row // 3) + i // 3][3 * (col // 3) + i // 3] == c):
                    return False
            return True

        if not board or len(board) <= 0: return             #判空，board是否为空
        for i in range(len(board)):                         #遍历行
            for j in range(len(board[i])):                  #遍历列
                if board[i][j] == '.':                      #如果该位置是空，则进入添加数据
                    for c in range(1,10):                   #遍历添加的数据1-9
                        if isvalid(board, i, j, str(c)):         #判断是否合格
                            board[i][j] = str(c)            #如果合格，则将其加入
                            if self.isValidSudoku(board):   #递归调用
                                return True                 #
                            else:
                                board[i][j] = '.'           #不符合就回溯添加‘.’
                    return False
        return True
    def printBoard(self,board):
        for i in range(len(board)):
            for j in range(len(board[i])):
                print(board[i][j],end=',')
            print()
if __name__ == '__main__':
    time1 = time.time()
    board = [
  ["5","3",".",".","7",".",".",".","."],
  ["6",".",".","1","9","5",".",".","."],
  [".","9","8",".",".",".",".","6","."],
  ["8",".",".",".","6",".",".",".","3"],
  ["4",".",".","8",".","3",".",".","1"],
  ["7",".",".",".","2",".",".",".","6"],
  [".","6",".",".",".",".","2","8","."], 
  [".",".",".","4","1","9",".",".","5"],
  [".",".",".",".","8",".",".","7","9"]
]
    solution = Solution()
    result =solution.isValidSudoku(board)
    solution.printBoard(board)
    time2 = time.time()
    print('run time:',time2-time1)