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。

解题思路

思路

代码实现

import java.util.Arrays;
class TreeNode {
     int val;
     TreeNode left;
     TreeNode right;
     TreeNode(int x) { val = x; }
 }


public class Solution {
    public TreeNode reConstructBinaryTree(int [] pre,int [] in) {
        
        
        if (pre.length == 0) {
            return null;
        }

        TreeNode node = null;
        for (int i = 0; i < in.length; i++) {
            if (pre[0] == in[i]) {
                 node = new TreeNode(pre[0]);
                 node.left = reConstructBinaryTree(
                         Arrays.copyOfRange(pre, 1, i+1),Arrays.copyOfRange(in, 0, i));
                 node.right = reConstructBinaryTree(
                         Arrays.copyOfRange(pre, i + 1, pre.length),
                        Arrays.copyOfRange(in, i + 1, in.length));
            }
        }
        return node;

}}