#csv

6 csv interview questions, asked at Amazon, Mercor, Scale AI and 3 more companies. Last asked Oct 2026.

Review a CSV-building function for correctness and performance bugsCodingYou are shown a short function (in Java or Python) that turns a table, a list of rows of string cells, into CSV text by appending to a string in a loop. Say what is wrong with its…
Last asked Oct 2026
Parse a raw CSV string and handle corrupted rowsCodingAnother team receives data as a raw CSV payload in one string. Write code that turns it into a data structure other teams can consume. Some rows are corrupted (wrong number of…
Last asked Sep 2026
CSV upload endpoint that classifies rows with an LLMCodingA practical round: build a service endpoint that takes an uploaded CSV, sends each row to a language model to classify it, and returns the results as JSON. Write the prompt and…
Last asked Jul 2026
Clean a CSV of transactionsCodingWrite a small pipeline that reads a CSV file of transactions, validates and normalizes each row (types, formats, missing values), decides what to do with rows that cannot be…
Last asked May 2026
Transaction fees from a CSV of paymentsCodingYou get payment transactions as a CSV string. Compute the fee for each one and the total fees per user. The rate depends on the payment type and provider and on the transaction's…
Last asked Apr 2026
Message latency from send and receive logsCodingTwo CSV files describe messages between two machines: one lists when machine A sent each message, the other when machine B received it. Match the rows by message and compute each…
Last asked Mar 2026