重建二叉树

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。

算法解析：参照   https://www.bilibili.com/video/BV1m7411V7TG?t=377

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
import java.util.Arrays;
public class Solution {
   public TreeNode reConstructBinaryTree(int[] pre, int[] in) {
        if (pre.length == 0 || in.length == 0) {
            return null;
        }
        TreeNode root = new TreeNode(pre[0]);
        for (int i = 0; i < in.length; i++) {
            // 在中序中找到前序的根
            if (pre[0] == in[i]) {
                /*
                    这里left与right的参数的大小互补
                 */
                root.left = reConstructBinaryTree(Arrays.copyOfRange(pre, 1, i + 1),
                        Arrays.copyOfRange(in, 0, i));
                root.right = reConstructBinaryTree(Arrays.copyOfRange(pre, i + 1, pre.length),
                        Arrays.copyOfRange(in, i + 1, in.length));
                break;
            }
        }
        return root;
    }
}