手写代码：两个平衡二叉树合并是怎么做的

参考回答：

首先，将两棵树分别展开为有序链表

public TreeNode prev = null;public void BSTtolinkedList(TreeNode root) {if (root == null) return;BSTtolinkedList(root.left);if (prev != null) {prev.right = root;prev.left = null;}prev = root;BSTtolinkedList(root.right);}

然后将两个有序链表合并

public TreeNode MergeTwolinkedList(TreeNode n1, TreeNode n2) {TreeNode head = new TreeNode();while (n1 != null && n2 != null) {if (n1.val < n2.val) {head.right = n1;n1 = n1.right;} else {head.right = n2;n2= n2.right;}head = head.right;}if (n1 != null) {head.right = n1;head = head.right;}if (n2 != null) {head.right = n2;head = head.right;}return head.right;}