word search

def exist_recursive(self,board,word,bot,rig,row,col):
        if len(word) == 0:
            return True
        if row >= bot or col >= rig or row < 0 or col < 0 or board[row][col] != word[0]:
            return False
        preserve = board[row][col]
        board[row][col] = "#"
        result = self.exist_recursive(board,word[1:],bot,rig,row+1,col) or self.exist_recursive(board,word[1:],bot,rig,row-1,col) or self.exist_recursive(board,word[1:],bot,rig,row,col+1) or self.exist_recursive(board,word[1:],bot,rig,row,col-1)
        board[row][col] = preserve
        return result
        
    def exist(self, board, word):
        if not board:
            return False
        for i in range(len(board)):
            for j in range(len(board[i])):
                if self.exist_recursive(board,word,len(board),len(board[i]),i,j) == True:
                    return True
        return False