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LetsGit.IT/Categories/Algorithms
Algorithmsmedium

Binary search on answer (parametric search): when is it applicable?

Tags
#binary-search#parametric-search#monotonic#optimization
Back to categoryPractice quiz

Answer

It applies when you can define a monotonic predicate over the answer space (e.g., “is there a solution with value ≤ X?”). Then you can binary search the minimal/maximal X that satisfies the predicate.

Advanced answer

Deep dive

Expanding on the short answer — what usually matters in practice:

  • Context (tags): binary-search, parametric-search, monotonic, optimization
  • 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 "binary-search-on-answer-(parametric-search):-whe"
function explain() {
  // Start from the core idea:
  // It applies when you can define a monotonic predicate over the answer space (e.g., “is ther
}

Common pitfalls

  • Too generic: no concrete trade-offs or examples.
  • Mixing average-case and worst-case (e.g., complexity).
  • Ignoring constraints: memory, concurrency, network/disk costs.

Interview follow-ups

  • When would you choose an alternative and why?
  • What production issues show up and how do you diagnose them?

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