重新二叉树

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。

package com.algorithm;

import java.util.Arrays;

//Definition for binary tree
  class TreeNode {
      int val;
      TreeNode left;
      TreeNode right;
      TreeNode(int x) { val = x; }
 }                            
 
public class ReconstructBinaryTree {
     public TreeNode reConstructBinaryTree(int [] pre,int [] in) {
        if(pre.length ==0 || in.length == 0) //判断长度是否为0
            return null;
        TreeNode treenode = new TreeNode(pre[0]);//新建每一个子节点的根节点
        for(int i = 0; i < in.length; i++){
            if(pre[0] == in[i]){
                treenode.left = reConstructBinaryTree(
                        Arrays.copyOfRange(pre, 1, i+1),
                        Arrays.copyOfRange(in, 0,i));
                treenode.right = reConstructBinaryTree(
                        Arrays.copyOfRange(pre, i+1, pre.length),
                        Arrays.copyOfRange(in, i+1, in.length));
            }
        }
        return treenode;
     }
     public static void main(String[] args) {
        int[] pre = {1,2,4,7,3,5,6,8};
        int[] in = {4,7,2,1,5,3,8,6};
        new ReconstructBinaryTree().reConstructBinaryTree(pre, in);
    }
     
}