Iterated two-phase local search for the colored traveling salesmen problem

The colored traveling salesmen problem (CTSP) is a generalization of the popular salesman with multiple salesmen. In CTSP, cities are divided into m exclusive city sets ( number salesmen) and one shared set. goal CTSP to determine shortest Hamiltonian circuit (also called route or tour) for each satisfying that (1) includes all an set some (or all) set, (2) included in unique route. relevant model practical applications known be computationally challenging. We present first iterated two-phase local search algorithm this important which combines optima exploration phase escaping phase. show computational results on 65 common benchmark instances demonstrate its effectiveness especially report 22 improved upper bounds. make source code publicly available facilitate use future research real applications.