LeetCode76|两颗二叉搜索树中的所有元素

输入：root1 = [2,1,4], root2 = [1,0,3]
输出：[0,1,1,2,3,4]
示例 2：

输入：root1 = [0,-10,10], root2 = [5,1,7,0,2]
输出：[-10,0,0,1,2,5,7,10]
示例 3：

输入：root1 = [], root2 = [5,1,7,0,2]
输出：[0,1,2,5,7]
示例 4：

输入：root1 = [0,-10,10], root2 = []
输出：[-10,0,10]

import java.util.*;

public class GetAllElementsTest2 {
    public static void main(String[] args) {
        TreeNode t11 = new TreeNode(2);
        TreeNode t12 = new TreeNode(1);
        TreeNode t13 = new TreeNode(4);
        t11.left = t12;
        t11.right = t13;

        TreeNode t21 = new TreeNode(1);
        TreeNode t22 = new TreeNode(0);
        TreeNode t23 = new TreeNode(3);

        t21.left = t22;
        t21.right = t23;
        List<Integer> allElements = getAllElements(t11, t21);
        System.out.println("allElements = " + allElements);

    }

    public static List<Integer> getAllElements(TreeNode root1, TreeNode root2) {
        List<Integer> list = new ArrayList<>();
        if (root1 == null && root2 == null) {
            return list;
        }
        List<Integer> list1 = getNode(root1);
        List<Integer> list2 = getNode(root2);
        list.addAll(list1);
        list.addAll(list2);
        Collections.sort(list);
        return list;

    }

    private static List<Integer> getNode(TreeNode root) {
        Queue<TreeNode> queue = new LinkedList<>();
        queue.add(root);
        List<Integer> list = new ArrayList<>();
        while (!queue.isEmpty()) {
            int size = queue.size();
            for (int i = 0; i < size; i++) {
                TreeNode node = queue.poll();
                if (node != null) {
                    list.add(node.val);
                    if (node.left != null) {
                        queue.add(node.left);
                    }
                    if (node.right != null) {
                        queue.add(node.right);
                    }
                }

            }
        }
        return list;
    }
}