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ConstructBinaryTreefromPreorderandInorderTraversal.h
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ConstructBinaryTreefromPreorderandInorderTraversal.h
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/*
Author: Annie Kim, [email protected]
Date: May 16, 2013
Problem: Construct Binary Tree from Preorder and Inorder Traversal
Difficulty: Easy
Source: http:https://leetcode.com/onlinejudge#question_105
Notes:
Given preorder and inorder traversal of a tree, construct the binary tree.
Note:
You may assume that duplicates do not exist in the tree.
Solution: Recursion.
*/
/**
* 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) {
return buildTreeRe(preorder.begin(), inorder.begin(), preorder.size());
}
TreeNode *buildTreeRe(vector<int>::iterator preorder, vector<int>::iterator inorder, int N) {
if (N <= 0) return NULL;
vector<int>::iterator it = find(inorder, inorder + N, *preorder);
int pos = it - inorder;
TreeNode *root = new TreeNode(*preorder);
root->left = buildTreeRe(preorder+1, inorder, pos);
root->right = buildTreeRe(preorder+1+pos, inorder+pos+1, N-1-pos);
return root;
}
};