[LeetCode] Construct Binary Tree from Inorder and Postorder Traversal

 1 /**
 2  * Definition for binary tree
 3  * struct TreeNode {
 4  *     int val;
 5  *     TreeNode *left;
 6  *     TreeNode *right;
 7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 8  * };
 9  */
10 class Solution {
11 public:
12     TreeNode *buildTree(vector<int> &inorder, vector<int> &postorder) {
13         if (inorder.empty() || postorder.empty())
14             return NULL;
15             return buildTree(inorder.begin(), inorder.end() - 1, postorder.begin(), postorder.end() - 1);
16         }
17     template<typename Iter>
18     TreeNode* buildTree(Iter inBegin, Iter inEnd, Iter postBegin, Iter postEnd) {
19         if (inBegin > inEnd) return nullptr;
20         if (postBegin > postEnd) return nullptr;
21         
22         TreeNode *root = new TreeNode(*postEnd);
23         Iter in_root_pos = find(inBegin, inEnd, *postEnd);
24         int left_length = in_root_pos - inBegin;
25         root->left = buildTree(inBegin, in_root_pos - 1, postBegin, postBegin + left_length - 1);
26         root->right = buildTree(in_root_pos + 1, inEnd, postBegin + left_length, postEnd - 1);
27         
28         return root;
29     }
30 };