递归和回溯_leetcode79

class Solution(object):
    def exist(self, board, word):
        """
        :type board: List[List[str]]
        :type word: str
        :rtype: bool
        """


        self.d = [[-1,0],[0,1],[1,0],[0,-1]]
        self.m = len(board)
        self.n = len(board[0])
        self.visit =[[False for i in range(self.n)] for j in range(self.m)]

        for x in range(0,self.m):
            for y in range(0,self.n):
                if self.searchWord(board,word,0,x,y):
                    return True

        return False

    def inArea(self,x,y):
        return x >= 0 and x < self.m  and  y >= 0 and y < self.n

    def searchWord(self,board,word,index,startX,startY):

        if index == len(word)-1:
            return board[startX][startY] == word[index]




        if board[startX][startY] == word[index]:

            self.visit[startX][startY] = True

            for item in self.d:
                newX = startX + item[0]
                newY = startY + item[1]

                if self.inArea(newX,newY) and self.visit[newX][newY] == False:
                    if self.searchWord(board,word,index+1,newX,newY):
                        return True

            self.visit[startX][startY] = False
            return False


        else:
            return False




s = Solution()

board =[
  ['A','B','C','E'],
  ['S','F','C','S'],
  ['A','D','E','E']
]



word = "ABCCED"

print s.exist(board,word)