Memetic algorithm with heuristic candidate list strategy for Capacitated Arc Routing Problem

Capacitated Arc Routing Problem (CARP) has drawn much attention during the last few years because of its applications in the real world. Recently, we developed a Memetic Algorithm with Extended Neighborhood Search (MAENS), which is powerful in solving CARP. The excellent performance of MAENS is mainly due to one of its local search operators, namely the Merge-Split (MS) operator. However, the higher computational complexity of the MS operator compared to traditional local search operators remains as the major drawback of MAENS, especially when applying it to large-size instances. In this paper, we propose a heuristic candidate list strategy to sample the neighbors generated by the MS operator instead of enumerating or sampling them randomly, in order to avoid unnecessary callings of the MS operator during local search. Based on the strategy, an improved algorithm of MAENS, namely MAENS-II, is developed. Experimental results on benchmark instances showed that MAENS-II managed to obtain the same level of solution quality as MAENS with much less computational time. This should be credited to the utilization of the proposed heuristic strategy. On the other hand, in case both MAENS and MAENS-II were provided comparable computational time, MAENS-II outperformed MAENS in terms of solution quality.