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Microsoft·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
May 2026

Summary

Microsoft coding screen, palindrome problem. Pretty standard but the follow-up about handling numbers without string conversion tripped me up more than I expected.

Questions Asked (1)

Q1

Write a function that checks if a given input (either a number or a string) is a palindrome.

Algorithms & Data StructuresTechnical Trade-offs
Author's notes

Started with the two-pointer approach, which felt solid.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the input types and edge cases, then propose a clean two-pointer approach for strings and a mathematical reversal for numbers. Discuss trade-offs between converting numbers to strings (simpler but uses extra space) versus reversing numerically (more efficient but careful with overflow). Finally, write pseudocode or actual code, and test with examples.

Pro tip: Mention that for numbers, you can avoid string conversion by reversing half the number to prevent overflow, and always discuss time/space complexity upfront to show algorithmic maturity.

1. Clarify requirements and edge cases

Ask about input types (integer, float, negative numbers, strings with spaces/punctuation), expected return type, and whether case sensitivity matters for strings.

2. Outline approaches and trade-offs

Present two main strategies: converting to string and using two pointers, or handling numbers mathematically by reversing digits. Compare time/space complexity and practicality.

3. Choose an approach and explain

Select the most suitable method based on constraints (e.g., string conversion for simplicity, mathematical for efficiency) and justify your choice.

4. Write pseudocode or code

Implement the solution step-by-step, handling edge cases like negative numbers (not palindromes) and single characters.

5. Test and optimize

Walk through test cases (e.g., 121, -121, 'racecar', 'hello') and discuss potential optimizations or alternative solutions.

Key Points to Mention

  • Time and space complexity of each approach (e.g., O(n) time, O(1) space for two-pointer on string; O(log n) time for numeric reversal).
  • Handling negative numbers: they are not palindromes due to the minus sign.
  • For strings: consider ignoring case, spaces, and punctuation if the problem allows.
  • For numbers: avoid integer overflow by reversing only half the number.
  • Edge cases: empty string, single character, trailing zeros (e.g., 10 is not a palindrome).
  • Trade-offs: string conversion is simpler but uses extra space; mathematical approach is more efficient but complex.

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