【LeetCode】Construct Binary Tree from Preorder and Inorder Traversal

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

Note:

You may assume that duplicates do not exist in the tree.
思路：同Construct
Binary Tree from Inorder and Postorder Traversal。

/**
* 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> &preorder, vector<int> &inorder) {
int N = preorder.size();
return buildTreeRe(inorder.begin(),preorder.begin(),N);
}
TreeNode *buildTreeRe(vector<int>::iterator inorder,vector<int>::iterator preorder,int N){
if(N <= 0)return NULL;
vector<int>::iterator it = find(inorder,inorder+N,*preorder);
int pos = it - inorder;
TreeNode* root = new TreeNode(*it);
root->left = buildTreeRe(inorder,preorder+1,pos);
root->right = buildTreeRe(inorder+pos+1,preorder+pos+1,N-pos-1);
return root;
}
};