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Meta·Software Engineer·Technical Phone Screen·Intermediate

IntermediatePrefer not to say
Jun 2026

Summary

Meta SWE coding round, one tree problem. Pretty straightforward session, nothing too wild.

Questions Asked (1)

Q1

Given a binary tree, return the values of the nodes visible from the right side, ordered from top to bottom.

Algorithms & Data Structures
Author's notes

Classic level-order traversal problem.

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AI HintsAI Generated

Suggested Approach

Use BFS level-order traversal, recording the last node's value at each level. Alternatively, use DFS prioritizing the right child and track the maximum depth seen so far to capture the rightmost node at each depth.

Pro tip: Clarify with the interviewer whether the tree can be empty or have only one node, and discuss the trade-offs between BFS and DFS in terms of space complexity and code simplicity.

1. Understand the problem

Confirm that 'visible from the right side' means the rightmost node at each depth level, and that the output should be ordered from top to bottom.

2. Choose an approach

Decide between BFS (level-order traversal) and DFS (right-first traversal with depth tracking). BFS is often more intuitive for level-based problems.

3. Implement BFS

Use a queue to process nodes level by level. For each level, record the value of the last node processed (the rightmost node).

4. Implement DFS (alternative)

Traverse right subtree first, then left. Keep track of the current depth and a list of results. If the current depth equals the list size, append the node's value.

5. Analyze complexity

State that both approaches run in O(n) time and O(n) space in the worst case (BFS queue or DFS recursion stack).

Key Points to Mention

  • BFS level-order traversal: process each level and take the last node.
  • DFS with right-first traversal and depth tracking.
  • Time complexity: O(n) where n is the number of nodes.
  • Space complexity: O(n) for BFS queue or O(h) for DFS recursion stack (h is tree height).
  • Edge cases: empty tree, single node, skewed tree.
  • Trade-offs: BFS uses more memory for wide trees, DFS may use less memory for balanced trees.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.