Microsoft·Software Engineer·Technical Phone Screen·Intermediate

Intermediate

Jun 2026

Summary

Microsoft SWE coding round, pretty straightforward data manipulation problem. Nothing too wild but it's the kind of thing that trips you up if you overthink it.

Questions Asked (1)

Given a list of row dictionaries where each dict maps column names to values, write a function that takes a column name and returns all values for that column across every row, in order.

Algorithms & Data StructuresAPI & Integrations

Author's notes

Basically a columnar slice of a list of dicts.

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AI HintsAI Generated

Suggested Approach

Clarify the input format and edge cases, then propose a simple list comprehension or loop that extracts the column values in order. Discuss time and space complexity, and mention how you would handle missing keys or empty input.

Pro tip: Demonstrate production awareness by discussing how to handle missing columns gracefully—e.g., using a default value or raising a clear error—and mention that the function should be efficient for large datasets.

1. Clarify requirements and edge cases

Ask about the expected behavior when a row lacks the specified column, when the list is empty, or when the column name is invalid. Confirm that order must be preserved.

2. Choose an appropriate data structure and algorithm

Decide between a list comprehension, a generator, or a loop with append. Consider using a default value for missing keys to avoid exceptions.

3. Write the function with clear code

Implement the function, ensuring it handles edge cases and returns a list of values in the original row order.

4. Analyze complexity and potential optimizations

State that the time complexity is O(n) where n is the number of rows, and space complexity is O(k) where k is the number of rows containing the column. Mention that no further optimization is needed for this simple extraction.

5. Test with examples and discuss integration

Walk through a few test cases, including missing keys and empty input. Briefly mention how this function might be used in a larger data processing pipeline.

Key Points to Mention

Order preservation: iterate through rows in the given order.
Handling missing keys: use dict.get() with a default or raise a KeyError with a clear message.
Time complexity: O(n) where n is the number of rows.
Space complexity: O(k) where k is the number of values returned.
Pythonic implementation: list comprehension or generator expression.
Edge cases: empty list, column not present in any row, non-string column names.

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