/**

 * Definition for a binary tree node.

 * struct TreeNode {

 *     int val;

 *     TreeNode *left;

 *     TreeNode *right;

 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}

 * };

 */

class Solution {

public:

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

        return DFS(preorder,,inorder,,inorder.size()-);

    }

    TreeNode* DFS(vector<int> preorder,int pos,vector<int> inorder,int ileft,int iright){

        if(ileft > iright) return NULL;

        int i=;

        for(i=ileft;i <= iright;i++){

            if(preorder[pos] == inorder[i])break;

        }

        TreeNode* cur = new TreeNode(preorder[pos]);

        cur->left = DFS(preorder,pos+,inorder,ileft,i-);

        cur->right = DFS(preorder,pos+i-ileft+,inorder,i+,iright);

        return cur;

    }

};