Selection Sort

Hook

Like choosing the shortest person from each remaining part of a line, selection sort fixes one position per pass.

Watch

Find one minimum at a time. Run best, average, worst and seeded random inputs; the animation is a reversible execution trace.

How it works

1. Keep a sorted prefix and an unsorted suffix.
2. Scan the suffix for its minimum.
3. Swap that minimum into the first unsorted position.

Try it

Pause at each decision and predict the operation before revealing its result. Input arrays are limited to 64 bounded integers.

Complexity

The comparison count stays quadratic even for a sorted input. Only at most n−1 swaps are needed.

Code

Choose a language in the code panel. The highlighted stage follows the trace; counters record the visualized reads, writes, comparisons and swaps.

When to use

Use it when writes are expensive and the input is tiny. It is usually slower than insertion sort on nearly sorted data.

Interview pitfalls

Swapping a distant minimum can reorder equal-key records; this version is not stable.

Quiz

Test the invariant and complexity below, then compare another algorithm on the same input.