1305. All Elements in Two Binary Search Trees

QUESTION:

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

Constraints:

The number of nodes in each tree is in the range [0, 5000].
-10^5 <= Node.val <= 10^5

EXPLANATION:

看似medium的题目, 其实是easy. 直接遍历两棵树, 添加到array中, 返回对array的排序即可.

SOLUTION:

class Solution {
    func getAllElements(_ root1: TreeNode?, _ root2: TreeNode?) -> [Int] {
        var result:[Int] = []
        getAllElementsHelper(root1, array: &result)
        getAllElementsHelper(root2, array: &result)
        return result.sorted()
    }
    
    func getAllElementsHelper(_ root:TreeNode?, array:inout [Int]) {
        if root==nil {
            return
        }
        getAllElementsHelper(root?.left, array: &array)
        array.append(root!.val)
        getAllElementsHelper(root?.right, array: &array)
    }
}
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