Question 1

How does the race mode decide the winner?

Accepted Answer

All lanes run on the exact same seeded input, and each algorithm records every comparison, swap and write as an operation. The trophy goes to the fewest total operations, shown per lane alongside comparison/swap/write counts. Operations measure engine work, not wall-clock milliseconds — constants differ per language and machine, but op counts make the asymptotic story visible.

Question 2

Why does QuickSort lose to MergeSort on sorted input?

Accepted Answer

The Lomuto partition takes the last element as its pivot. On already-sorted (or reverse-sorted) data every split is maximally unbalanced (0 / n−1), which degrades QuickSort to O(n²). MergeSort always splits in half, so its O(n log n) holds regardless of input. The Hoare variant and randomized pivots mitigate this — race all three to see it.

Question 3

Which pathfinding algorithm should I use?

Accepted Answer

On unweighted grids: BFS is the simple optimal answer. Dijkstra generalizes it to weighted edges. A* with a Manhattan heuristic is optimal on 4-neighbour grids and usually visits far fewer cells; the Euclidean variant stays admissible but expands more. Greedy Best-First is fastest but not optimal, and DFS only promises a path, not the shortest one.

Question 4

What does the sonification actually play?

Accepted Answer

Each comparison maps the compared value to pitch (low values low, high values high) through the shared Web Audio engine — the same one the synth tools use. Listening to a sort run gives you a feel for its access pattern: BubbleSort's sweeps sound like rising arpeggios, QuickSort's partitioning jumps between registers. Audio needs a click to start (browser autoplay policy) and can be toggled off any time.

Question 5

Are the trees real implementations?

Accepted Answer

Yes — AVL uses height bookkeeping with LL/RR/LR/RL rotations, Red-Black follows the CLRS insert fixup (recoloring and rotations, with invariant checks enforced by the test suite: black root, no red-red edges, uniform black height), the B-Tree is order 4 (2-3-4) with median promotion on overflow, and heaps sift down from the classic Floyd build. Duplicates are ignored for search trees, as in most textbook treatments.

Question 6

Can I trust the code snippets when porting?

Accepted Answer

The JavaScript, Python, Go and C++ snippets are line-aligned reference implementations that mirror the traced engine — the highlight follows the same statement in every language. They favor clarity over micro-optimization (e.g. recursive quicksort, not iterative with explicit stacks), so treat them as the canonical version to verify against, not as a tuned production library.

Question 7

Is the BogoSort real?

Accepted Answer

It shuffles until sorted, exactly as advertised — but bounded to 40 shuffles so it can never run away. When it gives up, the trace says so. It exists because watching it 'work' is the fastest way to appreciate why O(n·n!) is a joke, not a strategy.

Question 8

Does anything leave my browser?

Accepted Answer

No. Traces are computed in a Web Worker on your device (with an inline fallback where Workers are unavailable), mazes are seeded locally, and the only persistence is your own inputs in localStorage. There is no backend call in any tab.

Algorithm Arena & Data Structure Visualizer

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