string plus rolling hash Pattern
5 problems
Pattern pages help build reusable solving frames. Identify signals first, then explain state, transition, and edge handling.
Recognition Signals
- Understanding of rolling hash and string matching techniques.
- Ability to implement optimal algorithms for palindrome construction.
- Will you consider overlaps between prefix and suffix?
Solve Flow
- 1. Define the active state/window.
- 2. Update state while preserving invariants.
- 3. Validate with edge-heavy examples.
Common Misses
- Overcomplicating the solution by brute-forcing palindrome checks for each substring.
- Forgetting that the prefix cannot be the entire string itself.
- Counting even-length palindromes mistakenly, which violates the problem constraint.
Recommended Ladder
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