剑指offer重建二叉树

题目描述

输入某二叉树的前序遍历和中序遍历的结果，请重建出该二叉树。假设输入的前序遍历和中序遍历的结果中都不含重复的数字。例如输入前序遍历序列{1,2,4,7,3,5,6,8}和中序遍历序列{4,7,2,1,5,3,8,6}，则重建二叉树并返回。

参考答案

链接：https://www.nowcoder.com/questionTerminal/8a19cbe657394eeaac2f6ea9b0f6fcf6
来源：牛客网

 1 import java.util.*;
 2 /**
 3  * Definition for binary tree
 4  * public class TreeNode {
 5  *     int val;
 6  *     TreeNode left;
 7  *     TreeNode right;
 8  *     TreeNode(int x) { val = x; }
 9  * }
10  */
11 public class Solution {
12     public TreeNode reConstructBinaryTree(int [] pre,int [] in) {
13        if(pre.length == 0||in.length == 0){
14             return null;
15         }
16         TreeNode node = new TreeNode(pre[0]);
17         for(int i = 0; i < in.length; i++){
18             if(pre[0] == in[i]){
19                 node.left = reConstructBinaryTree(Arrays.copyOfRange(pre, 1, i+1), Arrays.copyOfRange(in, 0, i));
20                 node.right = reConstructBinaryTree(Arrays.copyOfRange(pre, i+1, pre.length), Arrays.copyOfRange(in, i+1,in.length));
21             }
22         }
23         return node;
24     }
25 }