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LetsGit.IT/Categories/Algorithms
Algorithmsmedium

Heap sort: what are its time complexity, space complexity, and stability?

Tags
#heapsort#sorting#complexity#stability
Back to categoryPractice quiz

Answer

Heapsort runs in O(n log n) time, uses O(1) extra space (in‑place), and is not stable (equal elements can change order).

Advanced answer

Deep dive

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

  • Context (tags): heapsort, sorting, complexity, stability
  • 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 "heap-sort:-what-are-its-time-complexity,-space-c"
function explain() {
  // Start from the core idea:
  // Heapsort runs in O(n log n) time, uses O(1) extra space (in‑place), and is not stable (equ
}

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?
  • How would you test edge cases?

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