add leetcode problem-cn part2

算法题（国内版）/problem (English)/后继者(English) [successor-lcci].html

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+<p>Write an algorithm to find the &quot;next&quot; node (i.e., in-order successor) of a given node in a binary search tree.</p>
+
+<p>Return <code>null</code> if there&#39;s no &quot;next&quot; node for the given node.</p>
+
+<p><strong>Example 1:</strong></p>
+
+<pre>
+<strong>Input:</strong> root = <code>[2,1,3], p = 1
+
+  2
+ / \
+1   3
+</code>
+<strong>Output:</strong> 2</pre>
+
+<p><strong>Example 2:</strong></p>
+
+<pre>
+<strong>Input:</strong> root = <code>[5,3,6,2,4,null,null,1], p = 6
+
+      5
+     / \
+    3   6
+   / \
+  2   4
+ /   
+1
+</code>
+<strong>Output:</strong> null</pre>