<p>Given two integer arrays, <code>preorder</code> and <code>postorder</code> where <code>preorder</code> is the preorder traversal of a binary tree of <strong>distinct</strong> values and <code>postorder</code> is the postorder traversal of the same tree, reconstruct and return <em>the binary tree</em>.</p>

<p>If there exist multiple answers, you can <strong>return any</strong> of them.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/07/24/lc-prepost.jpg" style="width: 304px; height: 265px;" />
<pre>
<strong>Input:</strong> preorder = [1,2,4,5,3,6,7], postorder = [4,5,2,6,7,3,1]
<strong>Output:</strong> [1,2,3,4,5,6,7]
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> preorder = [1], postorder = [1]
<strong>Output:</strong> [1]
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= preorder.length &lt;= 30</code></li>
	<li><code>1 &lt;= preorder[i] &lt;= preorder.length</code></li>
	<li>All the values of <code>preorder</code> are <strong>unique</strong>.</li>
	<li><code>postorder.length == preorder.length</code></li>
	<li><code>1 &lt;= postorder[i] &lt;= postorder.length</code></li>
	<li>All the values of <code>postorder</code> are <strong>unique</strong>.</li>
	<li>It is guaranteed that <code>preorder</code> and <code>postorder</code> are the preorder traversal and postorder traversal of the same binary tree.</li>
</ul>

class Solution {
public:
    void buildPrePost(
        std::vector<int> &pre, std::vector<int> &post,
        TreeNode *root, int &nextRoot, int l, int r
    ) {
        if (r > l) {
            int pivot = std::find(post.begin() + l, post.begin() + r, pre[nextRoot]) - post.begin();
            root->left = new TreeNode(pre[nextRoot]);
            buildPrePost(pre, post, root->left, ++nextRoot, l, pivot);
            if (pivot + 1 <= r - 1) {
                root->right = new TreeNode(pre[nextRoot]);
                buildPrePost(pre, post, root->right, ++nextRoot, pivot + 1, r - 1);
            }
        }
    }
    TreeNode* constructFromPrePost(vector<int>& pre, vector<int>& post) {
        TreeNode *root = nullptr;
        if (!pre.empty()) {
            root = new TreeNode(pre[0]);
            int nextRoot = 0;
            int pivot = post.size() - 1;
            buildPrePost(pre, post, root, ++nextRoot, 0, post.size() - 1);
        }
        return root;
    }
};

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