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LetsGit.IT/Categories/Algorithms
Algorithmshard

Kruskal vs Prim for MST — how do they differ?

Tags
#mst#kruskal#prim#graphs#big-o
Back to categoryPractice quiz

Answer

Kruskal sorts edges and adds the smallest ones that don’t create cycles (uses Union-Find). Prim grows a tree from a start node using a priority queue of edges. Both can be O(E log E) / O(E log V) depending on implementation.

Advanced answer

Deep dive

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

  • Context (tags): mst, kruskal, prim, graphs, big-o
  • 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 "kruskal-vs-prim-for-mst-—-how-do-they-differ?"
function explain() {
  // Start from the core idea:
  // Kruskal sorts edges and adds the smallest ones that don’t create cycles (uses Union-Find).
}

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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