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  2. 2 Additional Online Test (If Required)
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Problems > Exactly K Distinct > Editorial

Exactly K Distinct — Solution & Editorial

Back to the Problem

'Exactly K' = 'at most K' − 'at most K−1', each computed by a sliding window that counts, for every right endpoint, the number of valid left endpoints.

Complexity: O(N)

Watch out: The count reaches ~5×109 — 64-bit.