Implement and explain a function that receives a list of objects whose values are integers, a field name, and a mode `MIN` or `MAX`. Return the object containing that field whose value is best for the requested mode. Objects missing the field are ignored. If no object contains it, return no result. If multiple objects tie, return the earliest one in the input. Do not mutate the objects. ### Constraints & Assumptions - Field names are strings and present values are integers. - The list may be empty and objects may have different fields. - The implementation should make one pass and use constant auxiliary state. ### Clarifying Questions to Ask - Should a present `null` be treated as missing or invalid? - What deterministic tie rule is required? - Should malformed noninteger values fail the entire call or be skipped? ```hint Track presence separately Initializing the best value to zero is incorrect when every candidate is negative or the field is absent. ``` ### What a Strong Answer Covers - One-pass selection, missing-field handling, mode validation, and stable ties. - A clear return type and error policy. - Tests for empty input, negative values, duplicate extrema, absent keys, and invalid mode. ### Follow-up Questions - How would you return all tied objects? - How would the design change for a nested field path? - When would a reusable comparator be preferable to a mode flag?