Watch bubble, merge, quick, heap, and radix sort animate step by step. Compare speed and swap counts side by side.
Paste an array of numbers, or let the tool generate one, pick an algorithm from the five offered - bubble, merge, quick, heap, radix - and watch the sort run. The array renders as bars whose heights match the values, each step lights up the elements being compared or swapped, and swap totals tick up as the bars reorder. Running two algorithms side by side on identical input makes their personalities obvious: quicksort jumps across the array, bubble sort shuffles neighbors one position at a time, merge sort visibly assembles from halves. The surprise: the most visually frantic algorithm is rarely the one with the fewest swaps, and neither predicts runtime.
A concrete input and expected output from the current implementation.
Input
7, 2, 9, 4 with bubble sort selected
Expected output
Sorted: 2, 4, 7, 9. The animation logs 3 swaps - 7 with 2, then 9 with 4, then 7 with 4 - and stops after a quiet pass finds nothing to swap.
Bubble sort walks the array swapping adjacent pairs that are out of order, and the list has exactly three inversions - (7,2), (7,4), (9,4) - so three swaps remove them all. The passes themselves need six comparisons (three, then two, then one), which is why the animation keeps scanning even after the array looks sorted.
Each value maps to a bar whose height is the number, so the array reads as a skyline. Play runs the algorithm and pauses at each operation, highlighting the elements currently compared or swapped; step controls advance one operation at a time, and the speed control adjusts how fast passes replay. Swap totals accumulate as the animation runs, and a finished panel shows the fully sorted bars.
Bubble sort walks the array swapping adjacent out-of-order pairs until a pass makes no changes. Merge sort splits the array in half, recurses, and recombines sorted runs using a temporary array. Quicksort partitions around a pivot. Heapsort builds a max-heap and repeatedly extracts the largest element. Radix sort orders integers digit by digit. Side-by-side panels run all five on the same input, so swap counts and animation length are comparable.
Swaps are rare on nearly sorted data, but every pass still compares adjacent pairs across the whole array, and those comparisons are the O(n^2) part. On an almost-sorted list bubble sort makes near-minimum swaps yet scans the full array once per pass, so the animation lingers with nothing visibly changing. A quiet final pass is the tell: an early-exit implementation stops after any pass that makes no swaps.
It depends on the data. Quicksort is usually fastest on random input but can degrade to O(n^2) on already-sorted data with a poor pivot choice, while merge sort guarantees O(n log n) at the cost of a temporary array. Radix sort can beat every comparison-based sort on short integers. Run all five panels on the same array before trusting a ranking, and remember the speed control changes playback speed, not runtime.
The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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