hillclimb.shesc goes back
golomb-27
27 marks on a ruler, every pairwise distance distinct; make the ruler short. This is the problem by hand: what a search moves, you move.
Drag a mark; it snaps to integers. A distance the ruler measures twice shows in red, with both pairs arced. Scroll to zoom, drag empty space to pan, f fits. ⌘Z undoes.