Spacefilling curves and the planar travelling salesman problem
Loren K. Platzman, John J. Bartholdi · Journal of the ACM · 1989
To construct a short tour through points in the plane, the points are sequenced as they appear along a spacefilling curve. This heuristic consists essentially of sorting, so it is easily coded and requires only O ( N ) memory and O ( N log N ) operations. Its performance is competitive with that of other fast methods.