题解 | #重建二叉树#

import java.util.*; /**

• Definition for binary tree

• public class TreeNode {

• int val;
  

• TreeNode left;
  

• TreeNode right;
  

• TreeNode(int x) { val = x; }
  

• } */ //依据题解1写的 public class Solution { public TreeNode reConstructBinaryTree(int [] pre,int [] vin) { if(pre.length == 0) return null; TreeNode root = new TreeNode(pre[0]);//根节点

   int index = -1;//根节点在中序遍历的位置
   for(int i = 0;i < vin.length;i++) {
   	if(vin[i] == pre[0]) {
   		index = i;
   	}
   }
   
   int[] pre1 = Arrays.copyOfRange(pre, 1, index+1);
   int[] pre2 = Arrays.copyOfRange(pre, index+1, pre.length);
   int[] vin1 = Arrays.copyOfRange(vin, 0, index);
   int[] vin2 = Arrays.copyOfRange(vin, index+1, vin.length);
   
   root.left = reConstructBinaryTree(pre1, vin1);
   root.right = reConstructBinaryTree(pre2, vin2);
   
   return root;
  

  } }