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LetsGit.IT/Categories/Algorithms
Algorithmsmedium

Bellman–Ford: when do you use it and what extra capability does it have over Dijkstra?

Tags
#bellman-ford#shortest-path#graphs#negative-weights
Back to categoryPractice quiz

Answer

Use Bellman–Ford when you have negative edge weights. It can detect negative cycles by doing one extra relaxation round. The trade‑off is slower time complexity: O(V·E).

Advanced answer

Deep dive

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

  • Context (tags): bellman-ford, shortest-path, graphs, negative-weights
  • 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 "bellman–ford:-when-do-you-use-it-and-what-extra-"
function explain() {
  // Start from the core idea:
  // Use Bellman–Ford when you have negative edge weights. It can detect negative cycles by doi
}

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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