原題
給定一個二維的矩陣精绎，包含 'X' 和 'O'（字母 O）闰蛔。
找到所有被 'X' 圍繞的區(qū)域畅涂，并將這些區(qū)域里所有的 'O' 用 'X' 填充宛琅。
示例:
X X X X
X O O X
X X O X
X O X X
調(diào)用你的函數(shù)后，該二叉樹變?yōu)椋?/p>
X X X X
X X X X
X X X X
X O X X
思路
只有和最外層的‘O’不聯(lián)通的‘O’才會被‘X’替代蒋腮。使用深度優(yōu)先標(biāo)記所有和最外層‘O’聯(lián)通的‘O’為‘-’淘捡，再遍歷board將剩余的‘O’改寫成‘X’，‘-’改寫成‘O’池摧。
代碼
class Solution(object):
__row = None
__col = None
def solve(self, board):
"""
:type board: List[List[str]]
:rtype: void Do not return anything, modify board in-place instead.
"""
if not board or not board[0]:
return
self.__row = len(board)
self.__col = len(board[0])
for j in range(self.__row):
self.dfs(board, j, 0)
self.dfs(board, j, self.__col-1)
for i in range(self.__col):
self.dfs(board, 0, i)
self.dfs(board, self.__row-1, i)
for j in range(self.__row):
for i in range(self.__col):
if board[j][i] == 'O':
board[j][i] = 'X'
if board[j][i] == '-':
board[j][i] = 'O'
def dfs(self,board, j, i):
if 0<=i<self.__col and 0<=j<self.__row and board[j][i] == 'O':
board[j][i] = '-'
self.dfs(board,j-1,i)
self.dfs(board,j+1,i)
self.dfs(board,j,i-1)
self.dfs(board,j,i+1)
else:
return
