1305. All Elements in Two Binary Search Trees

문제

https://leetcode.com/problems/all-elements-in-two-binary-search-trees/description/

풀이

class Solution {
    List<Integer> list = new ArrayList<>();
    public List<Integer> getAllElements(TreeNode root1, TreeNode root2) {
        DFS(root1);
        DFS(root2);
        Collections.sort(list);
        return list;
    }

    public void DFS(TreeNode node) {
        if(node == null) {
            return;
        }

        list.add(node.val);
        DFS(node.left);
        DFS(node.right);

        return;
    }
}

• 각 노드를 순회하면서 List에 추가하고, 마지막에 오름차순으로 정렬 (O(NlogN))