Closest Version Date

Given a target version date and a list of released version dates, return the version whose date is closest to the target. The example target `2026-04-01` with versions `2023-04-01`, `2025-04-01`, and `2026-05-03` returns `2026-05-03`. Requirements Input: a target version date and a list of available version dates. Return the version date closest to the target date by calendar distance. Clarify tie-breaking before coding: earlier version, later version, or either acceptable. If the list is already sorted, use binary search around the insertion point; otherwise sort first or build the ordered index. Examples target = 2026-04-01 versions = [2023-04-01, 2025-04-01, 2026-05-03] answer = 2026-05-03 Notes The prompt was explicitly described as not being a direct LeetCode problem. Treat it like a production version-selection helper rather than a memorized LC template. Convert dates to comparable numeric values before taking differences; string comparison only works if the format is canonical ISO yyyy-mm-dd. Preparation Implement lower_bound on a sorted list and compare the predecessor / successor around the insertion index. Drill edge cases: target before all versions, after all versions, exact match, duplicate dates, and equidistant neighbors.