Day 24 — Sliding Window

What you’ll learn here

• Fixed-size windows — max sum of size k, average of last n elements, anagrams
• Variable-size windows — longest substring without repeating, minimum window substring
• The expand/contract template that solves most of them in ~10 lines
• Common pitfalls: forgetting to update the answer when contracting, off-by-one with right pointer

You already met sliding window in Sliding Window Maximum and Number of Recent Calls. This chapter formalizes the pattern.