Pattern 2: Sliding window
Comes up in: DSA
This concept is being written. It gets the full five steps — explanation, predict, interview angle, practice with tests, and review cards. Here is exactly what it will cover, so you can study it elsewhere in the meantime.
What it covers
- fixed vs variable window
- expand/shrink template with a hash map
- "longest/shortest subarray with condition"
- when windows fail (negative numbers → prefix sums)
Words you will know
What you will practise
- max-sum-subarray-k (E)
- buy-sell-stock (E)
- longest-substring-no-repeat (M)
- longest-repeating-char-replacement (M)
- permutation-in-string (M)
- fruit-baskets (M)
- min-window-substring (H)
Interview questions this answers
- How do you recognise a sliding-window problem?
- Why does the sliding window fail with negative numbers, and what do you use instead?