author: Daniel Maturana ([email protected])

A fast implementation of the vertex substitution heuristic for the p-median problem. Various of the optimizations suggested by M. Resende y R. Wernicke ('On the implementation of a swap based local search procedure for the p-median problem', Proceedings of the fifth workshop on Algorithm Engineering, 2003) were used.

This implemenentation won the GOCUP 2008 contest.

The program was developed in C++ using GNU g++ in Ubuntu Linux Hardy Heron. It was also verified to compile and run under Windows XP using the GNU MingW toolchain. It has no external library dependencies. To compile, simply run make. The program is named pmedian and accepts various arguments. The simplest usage is "pmedian " where number is the problem to solve. It includes various more options which can are documented in the help message which is displayed with "pmedian -h".

The project includes Joerg Arndt's bitarray implementation, which is part of the FXT library. The library is under GPLv3 as well.

While the algorithm is implemented for the general case, the data loading code is specialized for the contest format, which is 2-D. During development I tested on the classical ORLIB instances, after applying the Floyd-Warshall algorithm. I'll eventually reincorporate the code to read the ORLIB format.