This question evaluates a candidate's proficiency in array manipulation, distinct-element counting, and windowing techniques for optimizing contiguous-subarray queries. It is common in Coding & Algorithms interviews because it assesses algorithmic efficiency, the use of frequency-tracking data structures, and practical application-level problem solving rather than purely conceptual reasoning.
Given an integer array arr and an integer k, find the minimum length of a contiguous subarray that contains exactly k distinct integer values.
Return the minimum length, or -1 if no such subarray exists.
Constraints/notes:
arr
can contain duplicates.