LeetCode Construct Binary Tree from Inorder and Postorder Traversal

题目：

Given inorder and postorder traversal of a tree, construct the binary tree.

Note:

You may assume that duplicates do not exist in the tree.

/**
* 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> &inorder, vector<int> &postorder) {
TreeNode *root = createTree(inorder, 0, inorder.size()-1, postorder, 0, postorder.size()-1);
return root;
}
TreeNode *createTree(vector<int> &inorder, int inBeg, int inEnd, vector<int> &postorder, int postBeg, int postEnd) {
if(postBeg > postEnd)
return NULL;
int rootVal = postorder[postEnd];
int index;
for(int i = inBeg; i <= inEnd; i++) {
if(inorder[i] == rootVal) {
index = i;
break;
}
}
int len = index-inBeg;
TreeNode *root = new TreeNode(rootVal);
root->left = createTree(inorder, inBeg, index-1, postorder, postBeg, postBeg+len-1);
root->right = createTree(inorder, index+1, inEnd, postorder, postBeg+len, postEnd-1);
return root;
}
};