Software Engineer · Phone Screen · Coding

Stripe — Software Engineer ❌ Failed

Level: Junior-Level

Round: Phone Screen · Type: Coding · Difficulty: 4/10 · Duration: 60 min · Interviewer: Very Friendly

Topics: Strings, Hash Maps, Hash Sets

Location: Remote

Interview date: 2026-02-16

Got offer: False

Summary

Parse raw CSV transaction data into structured objects (handling edge cases like leading/trailing whitespace), then implement a transaction validation system that flags suspicious transactions by comparing transaction details against a blocklist using case-insensitive matching.

Details

Prompt: The interview was a 4-part progressive coding challenge.

Part 1: Parse a raw CSV string into structured transaction objects. Each row represented a transaction with fields like ID, amount, merchant, etc. Had to handle leading and trailing whitespace in field values.

Part 2: Implement case-insensitive matching to compare transaction details against a set of blocked/flagged values stored in a hashmap. Return whether each transaction is valid or flagged.

Parts 3-4: Did not reach these parts due to time constraints.

Assumptions/Constraints:

• CSV fields could have inconsistent spacing
• Matching was case-insensitive (e.g., "BLOCKED_MERCHANT" matches "blocked_merchant")
• Multiple fields could trigger a flag

Approach:

• Part 1: Split CSV by newline then by comma, trimmed whitespace from each field, mapped to transaction objects
• Part 2: Normalized all values to lowercase before inserting into hashmap and before lookup. Compared each transaction's fields against the blocklist.