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

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

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

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

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

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

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    TreeNode* build(vector<int>post,vector<int>in)
    {
       if(in.size()==1)
       {
        TreeNode* t=new TreeNode(in[0]);
        return t;
       }
       int x=post[post.size()-1];
       TreeNode* temp=new TreeNode(x);
    int it=find(in.begin(),in.end(),x)-in.begin();
    if(it==in.size()-1){
        temp->right=NULL;
        temp->left=build(vector<int>(post.begin(),post.end()-1),vector<int>(in.begin(),in.end()-1));
    }
    else if(it==0)
    {
        temp->left=NULL;
        temp->right=build(vector<int>(post.begin(),post.end()-1),vector<int>(in.begin()+1,in.end()));
    }
    else{
        temp->left=build(vector<int>(post.begin(),post.begin()+it),vector<int>(in.begin(),in.begin()+it));
        temp->right=build(vector<int>(post.begin()+it,post.end()-1),vector<int>(in.begin()+it+1,in.end()));
    }
     return temp;
    }
    TreeNode* buildTree(vector<int>& inorder, vector<int>& postorder) {
        return build(postorder,inorder);
    }
};
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