_1305.java

package com.fishercoder.solutions;

import com.fishercoder.common.classes.TreeNode;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

/**
 * 1305. All Elements in Two Binary Search Trees
 *
 * 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].*/
public class _1305 {
    public static class Solution1 {
        public List<Integer> getAllElements(TreeNode root1, TreeNode root2) {
            List<Integer> list1 = getAllNodes(root1);
            List<Integer> list2 = getAllNodes(root2);
            List<Integer> merged = new ArrayList<>();
            merged.addAll(list1);
            merged.addAll(list2);
            Collections.sort(merged);
            return merged;
        }

        private List<Integer> getAllNodes(TreeNode root) {
            List<Integer> list = new ArrayList<>();
            return inorder(root, list);
        }

        List<Integer> inorder(TreeNode root, List<Integer> result) {
            if (root == null) {
                return result;
            }
            inorder(root.left, result);
            result.add(root.val);
            return inorder(root.right, result);
        }
    }
}