Why Practice Sliding Window?
The Sliding Window pattern is the ultimate optimization for contiguous subarray and substring problems. It's one of the most frequently asked patterns in FAANG phone screens.
Hand-Picked Problems
| Problem | Difficulty | Key Pattern |
|---|---|---|
| Maximum Sum Subarray of Size K | Easy | Fixed Window |
| Longest Substring Without Repeating Characters | Medium | Variable (Set/Map) |
| Minimum Window Substring | Hard | Shortest Window |
| Longest Repeating Character Replacement | Medium | Max Freq Tracking |
| Fruit Into Baskets | Medium | Max K Distinct |
| Permutation in String | Medium | Anagram/Map Match |
| Sliding Window Maximum | Hard | Deque Hybrid |
| Subarray Product Less Than K | Medium | Product Counter |
| Longest Subarray of 1's After Deleting One Element | Medium | Zero Counter |
| Grumpy Bookstore Owner | Medium | Fixed Window Optimization |
Reflection Framework
For each problem you solve, write down:
- Fixed or Variable?
- Expansion Rule: When do I move
right? - Shrink Rule: When do I move
left? - Window State: What am I tracking (sum, frequency, max_count)?
Final Takeaway
Mastering these 10 problems will ensure you never get stuck on a contiguous range problem again.