# 统计封闭岛屿的数目

<p>有一个二维矩阵 <code>grid</code>&nbsp;，每个位置要么是陆地（记号为&nbsp;<code>0</code> ）要么是水域（记号为&nbsp;<code>1</code> ）。</p>

<p>我们从一块陆地出发，每次可以往上下左右&nbsp;4 个方向相邻区域走，能走到的所有陆地区域，我们将其称为一座「<strong>岛屿</strong>」。</p>

<p>如果一座岛屿&nbsp;<strong>完全</strong>&nbsp;由水域包围，即陆地边缘上下左右所有相邻区域都是水域，那么我们将其称为 「<strong>封闭岛屿</strong>」。</p>

<p>请返回封闭岛屿的数目。</p>

<p>&nbsp;</p>

<p><strong>示例 1：</strong></p>

<p><img src="https://assets.leetcode-cn.com/aliyun-lc-upload/uploads/2019/11/07/sample_3_1610.png"></p>

<pre><strong>输入：</strong>grid = [[1,1,1,1,1,1,1,0],[1,0,0,0,0,1,1,0],[1,0,1,0,1,1,1,0],[1,0,0,0,0,1,0,1],[1,1,1,1,1,1,1,0]]
<strong>输出：</strong>2
<strong>解释：</strong>
灰色区域的岛屿是封闭岛屿，因为这座岛屿完全被水域包围（即被 1 区域包围）。</pre>

<p><strong>示例 2：</strong></p>

<p><img src="https://assets.leetcode-cn.com/aliyun-lc-upload/uploads/2019/11/07/sample_4_1610.png"></p>

<pre><strong>输入：</strong>grid = [[0,0,1,0,0],[0,1,0,1,0],[0,1,1,1,0]]
<strong>输出：</strong>1
</pre>

<p><strong>示例 3：</strong></p>

<pre><strong>输入：</strong>grid = [[1,1,1,1,1,1,1],
&nbsp;            [1,0,0,0,0,0,1],
&nbsp;            [1,0,1,1,1,0,1],
&nbsp;            [1,0,1,0,1,0,1],
&nbsp;            [1,0,1,1,1,0,1],
&nbsp;            [1,0,0,0,0,0,1],
             [1,1,1,1,1,1,1]]
<strong>输出：</strong>2
</pre>

<p>&nbsp;</p>

<p><strong>提示：</strong></p>

<ul>
	<li><code>1 &lt;= grid.length, grid[0].length &lt;= 100</code></li>
	<li><code>0 &lt;= grid[i][j] &lt;=1</code></li>
</ul>

<p>以下错误的选项是？</p>

## aop

### before

```cpp

```
### after

```cpp

```

## 答案

```cpp

```

## 选项


### A

```cpp

```

### B

```cpp

```

### C

```cpp

```
