1602. Find Nearest Right Node in Binary Tree

Given the root of a binary tree and a node u in the tree, return the nearest node on the same level that is to the right of u, or return null if u is the rightmost node in its level.

Example 1:

Input: root = [1,2,3,null,4,5,6], u = 4
Output: 5
Explanation: The nearest node on the same level to the right of node 4 is node 5.

Example 2:

Input: root = [3,null,4,2], u = 2
Output: null
Explanation: There are no nodes to the right of 2.

Constraints:

• The number of nodes in the tree is in the range [1, 105].
• 1 <= Node.val <= 105
• All values in the tree are distinct.
• u is a node in the binary tree rooted at root.