Traveling Salesman Problem
Find a short tour on 1000 fixed cities.
This is the most classic problem. The tour must visit each city once and return to start. (See Wikipedia.)
Instance: N=1000 cities. The header line is "N", the city count. Then N lines "id x y".
Solution format: One line: the 1000 city ids separated by spaces, e.g. "0 1 2 5 4 3 ...".
Scoring: Total distance (smaller is better).
Solution example: 0 1 2 3 4 ... 999