## 题目描述：

LeetCode 529. Minesweeper

Let's play the minesweeper game (Wikipedia, online game)!

You are given a 2D char matrix representing the game board. 'M' represents an unrevealed mine, 'E' represents an unrevealed empty square, 'B' represents a revealed blank square that has no adjacent (above, below, left, right, and all 4 diagonals) mines, digit ('1' to '8') represents how many mines are adjacent to this revealed square, and finally 'X' represents a revealed mine.

Now given the next click position (row and column indices) among all the unrevealed squares ('M' or 'E'), return the board after revealing this position according to the following rules:

1. If a mine ('M') is revealed, then the game is over - change it to 'X'.
2. If an empty square ('E') with no adjacent mines is revealed, then change it to revealed blank ('B') and all of its adjacent unrevealed squares should be revealed recursively.
3. If an empty square ('E') with at least one adjacent mine is revealed, then change it to a digit ('1' to '8') representing the number of adjacent mines.
4. Return the board when no more squares will be revealed.

Example 1:

```Input:

[['E', 'E', 'E', 'E', 'E'],
['E', 'E', 'M', 'E', 'E'],
['E', 'E', 'E', 'E', 'E'],
['E', 'E', 'E', 'E', 'E']]

Click : [3,0]

Output:

[['B', '1', 'E', '1', 'B'],
['B', '1', 'M', '1', 'B'],
['B', '1', '1', '1', 'B'],
['B', 'B', 'B', 'B', 'B']]

Explanation: ```

Example 2:

```Input:

[['B', '1', 'E', '1', 'B'],
['B', '1', 'M', '1', 'B'],
['B', '1', '1', '1', 'B'],
['B', 'B', 'B', 'B', 'B']]

Click : [1,2]

Output:

[['B', '1', 'E', '1', 'B'],
['B', '1', 'X', '1', 'B'],
['B', '1', '1', '1', 'B'],
['B', 'B', 'B', 'B', 'B']]

Explanation: ```

Note:

1. The range of the input matrix's height and width is [1,50].
2. The click position will only be an unrevealed square ('M' or 'E'), which also means the input board contains at least one clickable square.
3. The input board won't be a stage when game is over (some mines have been revealed).
4. For simplicity, not mentioned rules should be ignored in this problem. For example, you don't need to reveal all the unrevealed mines when the game is over, consider any cases that you will win the game or flag any squares.

## 题目大意：

1. 输入矩阵的高度和宽度范围是[1, 50]。
2. 点击位置只会在'M'和'E'上，换言之，board中至少包含一个可以点击的方块。
3. 输入board不会处在游戏结束的状态。
4. 为了简化，未提到的规则可以忽略。例如，你不需要在游戏结束时翻开所有地雷，也不需要考虑是不是已经赢得游戏，或者在某些方块上插上了旗帜。

## Python代码：

``````class Solution(object):
def updateBoard(self, board, click):
"""
:type board: List[List[str]]
:type click: List[int]
:rtype: List[List[str]]
"""
w, h = len(board), len(board)
def countBoard(i, j):
cnt = 0
for di in (-1, 0, 1):
for dj in (-1, 0, 1):
ni, nj = i + di, j + dj
if ni < 0 or ni >= w or nj < 0 or nj >= h:
continue
if board[ni][nj] == 'M':
cnt += 1
return str(cnt) if cnt else 'B'
cx, cy = click
if board[cx][cy] == 'M':
board[cx][cy] = 'X'
return board
q = [click]
board[cx][cy] = countBoard(cx, cy)
if board[cx][cy] != 'B':
return board
while q:
ti, tj = q.pop(0)
for di in (-1, 0, 1):
for dj in (-1, 0, 1):
ni, nj = ti + di, tj + dj
if ni < 0 or ni >= w or nj < 0 or nj >= h:
continue
if board[ni][nj] == 'E':
board[ni][nj] = countBoard(ni, nj)
if board[ni][nj] == 'B':
q.append((ni, nj))
return board
``````

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