leetcode[106]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.

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
template<typename Iter>
void creatTree(TreeNode *&root,Iter inBeg,Iter inEnd, Iter posBeg,Iter posEnd)
{
    if(inBeg==inEnd||posBeg==posEnd)
    {
        root=NULL;
        return;
    }
    posEnd--;
    root=new TreeNode(*posEnd);
    Iter tmp=find(inBeg,inEnd,*posEnd);
    int leftsize=tmp-inBeg;
    creatTree(root->left,inBeg,tmp,posBeg,posBeg+leftsize);
    creatTree(root->right,tmp+1,inEnd,posBeg+leftsize,posEnd);
}
TreeNode *buildTree(vector<int> &inorder, vector<int> &postorder) 
{
    TreeNode *root;
    creatTree(root,inorder.begin(),inorder.end(),postorder.begin(),postorder.end());
    return root;        
}
};