/**
* 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* getTree(vector<int> &preorder, vector<int> &inorder, int prebeg, int preend, int inbeg, int inend)
{
if(prebeg < preend && inbeg < inend)
{
TreeNode *rev = new TreeNode(preorder[prebeg]);
vector<int>::iterator mid = find(inorder.begin()+inbeg, inorder.begin()+inend, preorder[prebeg]);
int span = mid - (inorder.begin() + inbeg);
rev->left = getTree(preorder, inorder, prebeg+1, prebeg+1+span, inbeg, inbeg+span);
rev->right = getTree(preorder, inorder, prebeg+1+span, preend, inbeg+span+1, inend);
return rev;
}
return NULL;
}
TreeNode *buildTree(vector<int> &preorder, vector<int> &inorder) {
return getTree(preorder, inorder, 0, preorder.size(), 0, inorder.size());
}
};