A rolling hash lets you update the hash of a window when you shift by one character (remove left, add right). Rabin–Karp compares hashes to find candidate matches, then usually verifies the substring to avoid false positives. Caveat: hashes can collide, so without verification it’s not guaranteed correct.
Advanced answer
Deep dive
Expanding on the short answer — what usually matters in practice:
Complexity: compare typical operations (average vs worst-case).
Invariants: what must always hold for correctness.
When the choice is wrong: production symptoms (latency, GC, cache misses).
Explain the "why", not just the "what" (intuition + consequences).
Trade-offs: what you gain/lose (time, memory, complexity, risk).
Edge cases: empty inputs, large inputs, invalid inputs, concurrency.
Examples
A tiny example (an explanation template):
// Example: discuss trade-offs for "rabin–karp:-what-is-a-rolling-hash-and-what-is-t"
function explain() {
// Start from the core idea:
// A rolling hash lets you update the hash of a window when you shift by one character (remov
}
Common pitfalls
Too generic: no concrete trade-offs or examples.
Mixing average-case and worst-case (e.g., complexity).