modify columns core interview pattern Pattern
1 problems
Pattern pages help build reusable solving frames. Identify signals first, then explain state, transition, and edge handling.
Recognition Signals
- Emphasize vectorized column operations.
- Check if the candidate avoids unnecessary loops.
Solve Flow
- 1. Define the active state/window.
- 2. Update state while preserving invariants.
- 3. Validate with edge-heavy examples.
Common Misses
- Using explicit for-loops over rows, which is slower.