LeetCode *** 106. 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.

分析：

我都不知道怎么回事，出错次数太多了，搞得自己都没信心了。

代码：

/**
* Definition for a binary tree node.
* 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) {
if(inorder.empty()||inorder.size()!=postorder.size())return NULL;
int val=*(postorder.end()-1);
TreeNode* root=new TreeNode(val);
int i=0;
while(inorder[i]!=val)i++;

root->left=buildTree(inorder,0,i-1,postorder,0,i-1);
root->right=buildTree(inorder,i+1,inorder.size()-1,postorder,i,inorder.size()-2);
return root;

}

TreeNode* buildTree(vector<int>& inorder,int is,int ie, vector<int>& postorder,int ps,int pe){
if(is>ie)return NULL;

int val=postorder[pe];
TreeNode* root=new TreeNode(val);
int i=is;
while(inorder[i]!=val)i++;
root->left=buildTree(inorder,is,i-1,postorder,ps,ps+i-is-1);
root->right=buildTree(inorder,i+1,ie,postorder,ps+i-is,pe-1);
return root;
}

};