Sliding Window Problems | Young Devs Bin

3. Longest Substring Without Repeating Characters — HashSet works, but HashMap lets you jump left directly instead of moving one step at a time
424. Longest Repeating Character Replacement — maxf never decreases; window only grows when we find something better
340. Longest Substring with At Most K Distinct Characters — generalized version of 159
159. Longest Substring with At Most Two Distinct Characters — same as 340, just K = 2
992. Subarrays with K Different Integers — exactly K = atMost(K) - atMost(K-1), also solvable with 3-pointer trick