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.

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    TreeNode *buildTree(vector<int> &inorder, vector<int> &postorder) {
        return buildTreeRe(inorder.begin(), postorder.begin(), inorder.size());
    }
    
    TreeNode* buildTreeRe(vector<int>::iterator inorder, vector<int>::iterator postorder, int N)
    {
        if(N <= 0) return NULL;
        vector<int>::iterator it = find(inorder, inorder + N, *(postorder+N-1));
        TreeNode* root = new TreeNode(*(postorder+N-1));
        int pos = it - inorder;
        root->left = buildTreeRe(inorder, postorder, pos);
        root->right = buildTreeRe(inorder + pos + 1, postorder + pos, N - pos - 1);
        return root;
    }
};