construct-binary-tree-from-preorder-and-inorder-traversal

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Algorithms

Given two integer arrays <code>preorder</code> and <code>inorder</code> where <code>preorder</code> is the preorder traversal of a binary tree and <code>inorder</code> is the inorder traversal of the same tree, construct and return the binary tree.

&nbsp;
Example 1:
<img alt="" src="https://assets.leetcode.com/uploads/2021/02/19/tree.jpg" style="width: 277px; height: 302px;" />
<pre>
Input: preorder = [3,9,20,15,7], inorder = [9,3,15,20,7]
Output: [3,9,20,null,null,15,7]
</pre>

Example 2:

<pre>
Input: preorder = [-1], inorder = [-1]
Output: [-1]
</pre>

&nbsp;
Constraints:

<ul>
	<li><code>1 &lt;= preorder.length &lt;= 3000</code></li>
	<li><code>inorder.length == preorder.length</code></li>
	<li><code>-3000 &lt;= preorder[i], inorder[i] &lt;= 3000</code></li>
	<li><code>preorder</code> and <code>inorder</code> consist of unique values.</li>
	<li>Each value of <code>inorder</code> also appears in <code>preorder</code>.</li>
	<li><code>preorder</code> is guaranteed to be the preorder traversal of the tree.</li>
	<li><code>inorder</code> is guaranteed to be the inorder traversal of the tree.</li>
</ul>