leetcode - Construct Binary Tree from Preorder and Inorder Traversal

/**
* 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>::iterator inBegin, vector<int>::iterator inEnd,
vector<int>::iterator preBegin, vector<int>::iterator preEnd){
int val = *(preBegin);
TreeNode * root = new TreeNode(val);
vector<int>::iterator ii, jj;
for (ii=inBegin, jj=preBegin+1; ii!=inEnd && *ii!=val; ii++, jj++);
if (ii!=inBegin)
root->left = buildTree(inBegin, ii, preBegin+1, jj);
if (ii+1 != inEnd)
root->right = buildTree(ii+1, inEnd, jj, preEnd);
return root;
}
TreeNode *buildTree(vector<int> &preorder, vector<int> &inorder) {
// Start typing your C/C++ solution below
// DO NOT write int main() function
if (inorder.empty())
return NULL;
return buildTree(inorder.begin(),inorder.end(),preorder.begin(), preorder.end());
}
};