LeetCode: 106_Construct Binary Tree from Inorder and Postorder Traversal | 根据中序和后序遍历构建二叉树 | Medium

要求：根据中序和后序遍历序列构建一棵二叉树

代码如下：

 1 struct TreeNode {
 2     int            val;
 3     TreeNode    *left;
 4     TreeNode    *right;
 5     TreeNode(int x): val(x),left(NULL), right(NULL) {}
 6 };
 7 
 8 typedef vector<int>::iterator Iter;
 9 
10 TreeNode *buildTreeFromInorderPostorder(vector<int> &inorder, vector<int> &postorder)
11 {
12     return buildBinaryTreeResur(inorder.begin(), inorder.end(), postorder.begin(), postorder.end());
13 }
14 
15 TreeNode *buildBinaryTreeResur(Iter istart, Iter iend, Iter pstart, Iter pend)
16 {
17     if (istart == iend || pstart == pend)
18         return NULL;
19     int ival = *(pend-1);
20     Iter ptemp = find(istart, iend, ival);
21     TreeNode *res = new TreeNode(ival);
22     res->left = buildBinaryTreeResur(istart, ptemp, pstart, pstart+(ptemp-istart));
23     res->right = buildBinaryTreeResur(ptemp+1, iend, pstart+(ptemp-istart), pend-1);
24     return res;
25 }