Detect duplicates / near-duplicates in streaming events

Given a stream of integer event IDs in arrival order, determine whether any duplicate ID appears within any sliding window of size k. Input: Line 1: n k Line 2: n integers, the ID sequence Output: Print true if there exists a window where a duplicate occurs within distance k; otherwise print false. Constraints: 1 <= n <= 2e5 0 <= k <= 2e5 IDs are 32-bit signed ints Examples: 5 3 / 1 2 3 1 5 -> true 5 2 / 1 2 3 1 5 -> false 4 0 / 1 1 1 1 -> false 1 1 / 7 -> false 6 3 / 1 2 3 4 5 6 -> false Example Input 5 3 1 2 3 1 5 Output true