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)