Fast shortest-paths algorithms in the presence of few destinations of negative-weight arcs

  • Authors:
  • Domenico Cantone;Simone Faro

  • Affiliations:
  • -;-

  • Venue:
  • Journal of Discrete Algorithms
  • Year:
  • 2014

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Abstract

In this paper we present hybrid algorithms for the single-source shortest-paths (SSSP) and for the all-pairs shortest-paths (APSP) problems, which are asymptotically fast when run on graphs with few destinations of negative-weight arcs. Plainly, the case of graphs with few sources of negative-weight arcs can be handled as well, using reverse graphs. With a directed graph with n nodes and m arcs, our algorithm for the SSSP problem has an O(@?(m+nlogn+@?^2))-time complexity, where @? is the number of destinations of negative-weight arcs in the graph. In the case of the APSP problem, we propose an O(nm^@?+n^2logn+@?n^2) algorithm, where m^@? is the number of arcs participating in shortest paths. Notice that m^@? is likely to be small in practice, since m^@?=O(nlogn) with high probability for several probability distributions on arc weights.