leetcode1305，All Elements in Two Binary Search Trees

leetcode 1305题
Given two binary search trees root1 and root2.

Return a list containing all the integers from both trees sorted in ascending order.

Example 1:

Input: root1 = [2,1,4], root2 = [1,0,3]
Output: [0,1,1,2,3,4]
Example 2:

Input: root1 = [0,-10,10], root2 = [5,1,7,0,2]
Output: [-10,0,0,1,2,5,7,10]
Example 3:

Input: root1 = [], root2 = [5,1,7,0,2]
Output: [0,1,2,5,7]
Example 4:

Input: root1 = [0,-10,10], root2 = []
Output: [-10,0,10]
Example 5:

Input: root1 = [1,null,8], root2 = [8,1]
Output: [1,1,8,8]

Constraints:

Each tree has at most 5000 nodes.
Each node’s value is between [-10^5, 10^5].

本题解题报告见 leetcode题解1305