[剑指offer]重建二叉树

思路：

实现：

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
import java.util.*;
public class Solution {
    public TreeNode reConstructBinaryTree(int [] pre,int [] in) {
        if(pre.length==0 || in.length==0){
            return null;
        }
        TreeNode node=new TreeNode(pre[0]);
        for(int i=0;i<in.length;i++){
            if(pre[0]==in[i]){
                node.left=reConstructBinaryTree(Arrays.copyOfRange(pre,i,i+1),Arrays.copyOfRange(in,0,i));
                node.right=reConstructBinaryTree(Arrays.copyOfRange(pre,i+1,pre.length),Arrays.copyOfRange(in,in+1,in.length));
            }
        }
        return node;
    }
}