Construct Binary Tree from Inorder and Postorder Traversal

Given inorder and postorder traversal of a tree, construct the binary tree.

Note:

You may assume that duplicates do not exist in the tree.

#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;

struct TreeNode {
int val;
TreeNode *left;
TreeNode *right;
TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};
TreeNode *CreatTree(vector<int>::iterator in_begin, vector<int>::iterator in_end, vector<int>::iterator pos_begin, vector<int>::iterator pos_end )
{
if (in_begin == in_end)
return NULL;

vector<int>::iterator Rootpos = pos_end-1;
vector<int>::iterator Rootino = find(in_begin, in_end, *Rootpos);
auto lenleft = distance(in_begin, Rootino);
TreeNode *root = new TreeNode(*Rootpos);
root->left  = CreatTree(in_begin, Rootino, pos_begin, pos_begin + lenleft);
root->right = CreatTree(Rootino + 1, in_end, pos_begin + lenleft, Rootpos);
return root;

}
TreeNode *buildTree(vector<int> &inorder, vector<int> &postorder) {

if (inorder.empty())
return NULL;
TreeNode *Root = new TreeNode(0);
Root = CreatTree(inorder.begin(), inorder.end(), postorder.begin(), postorder.end());
return Root;
}