Essential Coding Patterns: Two-Pointers & Sliding Window
Recognize pattern signatures for Two-Pointers, Sliding Window, Fast/Slow Pointers, and Top-K Heap algorithms.
Algorithmic Pattern Signatures
### Pattern Recognition
- **Two-Pointers**: Sorted arrays/strings searching for pairs (`left=0, right=n-1`). Time: $O(N)$.
- **Sliding Window**: Subarray/substring contiguous windows (e.g. longest substring without repeating characters). Time: $O(N)$.
- **Fast & Slow Pointers (Floyd Cycle)**: Linked list cycle detection and middle node discovery.
