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.

Solution: Recursion.

 1 /**
 2  * Definition for binary tree
 3  * struct TreeNode {
 4  *     int val;
 5  *     TreeNode *left;
 6  *     TreeNode *right;
 7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 8  * };
 9  */
10 class Solution {
11 public:
12     TreeNode *buildTree(vector<int> &inorder, vector<int> &postorder) {
13         return buildTreeRe(inorder.begin(), postorder.begin(), inorder.size());
14     }
15     
16     TreeNode* buildTreeRe(vector<int>::iterator inorder, vector<int>::iterator postorder, int N)
17     {
18         if(N <= 0) return NULL;
19         vector<int>::iterator it = find(inorder, inorder + N, *(postorder+N-1));
20         TreeNode* root = new TreeNode(*(postorder+N-1));
21         int pos = it - inorder;
22         root->left = buildTreeRe(inorder, postorder, pos);
23         root->right = buildTreeRe(inorder + pos + 1, postorder + pos, N - pos - 1);
24         return root;
25     }
26 };