Start by clarifying the requirements and edge cases, then outline a step-by-step parsing algorithm before writing code. Focus on splitting the query string into segments, parsing each segment into key-value pairs, and aggregating repeated keys into lists while handling type conversions and boolean flags.
Pro tip: Demonstrate production awareness by discussing how you would handle malformed input, URL encoding, and performance for large query strings, and mention that you would write unit tests for edge cases like empty values, repeated keys, and quoted strings with special characters.
Ask questions to confirm the expected behavior for ambiguous cases such as empty values, keys without values, URL-encoded characters, and values that look like numbers but should remain strings. This ensures you build the right solution.
Outline a plan: split the query string by '&', then for each segment, check if it starts with '!' and has no '=' (boolean flag), otherwise split on the first '=' into key and value. Parse the value into int, bool, or string, unquoting if necessary.
Use a map to accumulate values. If a key is seen again, convert the existing value into a list and append the new value. Ensure that boolean flags are also aggregated correctly if repeated.
For each value, attempt to parse as integer, then boolean ('true'/'false'), otherwise treat as string. If the value is enclosed in quotes, remove the quotes and treat as string without further type conversion.
Walk through test cases including repeated keys, mixed types, quoted strings, and boolean flags. Discuss trade-offs such as using a single pass vs. multiple passes, and how to handle URL decoding.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.