Approximate TSP using Sierpinski curve

https://www2.isye.gatech.edu/~jjb/research/mow/mow.html

A useful property of a spacefilling curve is that it tends to visit all the points in a region once it has entered that region. Thus points that are close together in the plane will tend to be close together in appearance along the curve.

This forms the basis of the heuristic, invented by L. Platzman and me, to produce a reasonably short tour of n given locations (the so-called Travelling Salesman's Tour): Simply visit them in the same sequence as does the spacefilling curve. For example, a short tour of the points marked in read is indicated by the green lines, which connect the points in the same sequence as their appearance on the spacefilling curve