# 力扣130. 被围绕的区域


## 力扣130. Surrounded Regions（被围绕的区域）

给你一个 m×n 的矩阵 board，由若干字符 'X' 和 'O' 组成。找到所有被 'X' 围绕的区域，并将这些区域里所有的 'O' 用 'X' 填充。

示例 1：

![](../posts/01_学习/87_LeetCode/0130_被围绕的区域/img/0130-1-description.png)

```
输入：board = [["X","X","X","X"],["X","O","O","X"],["X","X","O","X"],["X","O","X","X"]]
输出：[["X","X","X","X"],["X","X","X","X"],["X","X","X","X"],["X","O","X","X"]]
解释：被围绕的区域不会存在于边界上，换句话说，任何边界上的 'O' 都不会被填充。任何不在边界上，或不与边界上的 'O' 相连的 'O' 最终都会被填充。
```

提示：
- m == board.length
- n == board[i].length
- 1 <= m, n <= 200
- board[i][j] 为 'X' 或 'O'