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Upstart·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
Apr 2026

Summary

Straightforward coding screen for a software engineer role at Upstart. One question, pretty short session, nothing too wild.

Questions Asked (1)

Q1

Given a list of integers, return a reversed version of the list with all odd numbers removed.

Algorithms & Data Structures
Author's notes

Easier than I expected.

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AI HintsAI Generated

Suggested Approach

First, clarify the problem requirements and edge cases with the interviewer. Then, discuss a straightforward approach using a single pass to filter out odd numbers and reverse the result, analyzing its time and space complexity. Finally, implement the solution in code, test it with examples, and consider potential optimizations or alternative approaches.

Pro tip: Demonstrate your thought process by explicitly stating assumptions (e.g., whether to modify the input in-place or return a new list) and discussing trade-offs between clarity and efficiency. This shows maturity and prevents misunderstandings.

1. Clarify requirements and edge cases

Ask questions to confirm input/output types, whether the input can be modified, and how to handle empty lists or lists with all odd/even numbers. This ensures alignment with the interviewer's expectations.

2. Outline a high-level approach

Propose a simple method: iterate through the list, collect even numbers, then reverse the collection. Alternatively, iterate from the end and collect even numbers to avoid a separate reversal step.

3. Analyze complexity and trade-offs

State the time complexity (O(n)) and space complexity (O(n) for a new list, O(1) extra if in-place). Discuss whether an in-place solution is feasible and its implications.

4. Implement and test

Write clean code for the chosen approach, using appropriate language constructs (e.g., list comprehensions in Python). Walk through a test case to verify correctness, including edge cases.

5. Consider optimizations or alternatives

Mention if the problem can be solved with a single pass without extra space (e.g., using two pointers if in-place is allowed). Discuss readability vs. efficiency.

Key Points to Mention

  • Time and space complexity analysis (O(n) time, O(n) or O(1) space depending on approach)
  • Edge cases: empty list, all odd numbers, all even numbers, single element
  • Choice of data structures (e.g., using a list or deque for efficient reversal)
  • In-place vs. out-of-place modification and its impact on space complexity
  • Language-specific idioms (e.g., Python list comprehensions, filter, reversed)
  • Testing strategy: unit tests, boundary cases, and validation with examples

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