Is Find Nearest Right Node in Binary Tree easy or hard?

The problem is generally classified as Medium difficulty. The main challenge is recognizing that the nearest right node must exist in the same level, which naturally leads to a BFS level-order traversal strategy.

Find Nearest Right Node in Binary Tree Python/Java solution

Most implementations use a queue for BFS. Push the root into the queue, process nodes level by level, and track the number of nodes per level. When the target node appears, return the next node in the queue if it belongs to the same level. The same logic translates directly to Python, Java, C++, Go, and JavaScript.

How to solve Find Nearest Right Node in Binary Tree in O(n)?

Use a BFS level-order traversal. For each level, record the number of nodes currently in the queue. When the target node is encountered, return the next node in that level if it exists; otherwise return null. This guarantees a single pass through all nodes.

What is the best approach for Find Nearest Right Node in Binary Tree?

Breadth-First Search (level order traversal) is the most efficient and intuitive approach. Process the tree level by level using a queue. When the target node appears, check if another node exists in the same level immediately after it. This solution runs in O(n) time and O(n) space.

Is Find Nearest Right Node in Binary Tree asked at Google/Amazon/Meta?

Binary tree traversal problems like this frequently appear in interviews at companies such as Amazon, Google, and Meta. Variants that require level-order traversal or neighbor detection in trees are especially common in system design and algorithm rounds.

What data structure is used in Find Nearest Right Node in Binary Tree?

A queue is the primary data structure for the optimal BFS solution. It maintains nodes in level order so neighbors at the same depth appear sequentially. The DFS alternative may use recursion and a hash map or list to group nodes by depth.

What is the time complexity of Find Nearest Right Node in Binary Tree?

The optimal solution runs in O(n) time because each node in the binary tree is visited once during traversal. Space complexity is O(n) in the worst case due to the queue used in BFS or the level storage used in DFS.

Description Hints 4 Solution Video 5:33

1602. Find Nearest Right Node in Binary Tree

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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.

Asked at 1 company

Google

Topics

Hints open one at a time

Hint 1

Use BFS, traverse the tree level by level and always push the left node first

Hint 2

When you reach the target node, mark a boolean variable true

Hint 3

If you meet another node in the same level after marking the boolean true, return this node.

Hint 4

If you did not meet new nodes in the same level and started traversing a new level, return Null

5:33

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Starter codePython 3Spaces: 4

Examples

Case 1Case 2

Input

[1,2,3,null,4,5,6]
4

Input

[3,null,4,2]
2

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