add leetcode problem-cn part1

算法题（国内版）/problem (English)/统计封闭岛屿的数目(English) [number-of-closed-islands].html

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+<p>Given a 2D&nbsp;<code>grid</code> consists of <code>0s</code> (land)&nbsp;and <code>1s</code> (water).&nbsp; An <em>island</em> is a maximal 4-directionally connected group of <code><font face="monospace">0</font>s</code> and a <em>closed island</em>&nbsp;is an island <strong>totally</strong>&nbsp;(all left, top, right, bottom) surrounded by <code>1s.</code></p>
+
+<p>Return the number of <em>closed islands</em>.</p>
+
+<p>&nbsp;</p>
+<p><strong>Example 1:</strong></p>
+
+<p><img alt="" src="https://assets.leetcode.com/uploads/2019/10/31/sample_3_1610.png" style="width: 240px; height: 120px;" /></p>
+
+<pre>
+<strong>Input:</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>Output:</strong> 2
+<strong>Explanation:</strong> 
+Islands in gray are closed because they are completely surrounded by water (group of 1s).</pre>
+
+<p><strong>Example 2:</strong></p>
+
+<p><img alt="" src="https://assets.leetcode.com/uploads/2019/10/31/sample_4_1610.png" style="width: 160px; height: 80px;" /></p>
+
+<pre>
+<strong>Input:</strong> grid = [[0,0,1,0,0],[0,1,0,1,0],[0,1,1,1,0]]
+<strong>Output:</strong> 1
+</pre>
+
+<p><strong>Example 3:</strong></p>
+
+<pre>
+<strong>Input:</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>Output:</strong> 2
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</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>