Fully Dynamic Shortest Paths and Negative Cycles Detection on Digraphs with Arbitrary Arc Weights

  • Authors:
  • Daniele Frigioni;Alberto Marchetti-Spaccamela;Umberto Nanni

  • Affiliations:
  • -;-;-

  • Venue:
  • ESA '98 Proceedings of the 6th Annual European Symposium on Algorithms
  • Year:
  • 1998

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Abstract

We study the problem of maintaining the distances and the shortest paths from a source node in a directed graph with arbitrary arc weights, when weight updates of arcs are performed. We propose algorithms that work for any graph and require linear space and optimal query time. If a negative{length cycle is added during weight-decrease operations it is detected by the algorithms. The algorithms explicitly deal with zero{length cycles. We show that, if the graph has a k-bounded accounting function (as in the case of graphs with genus, arboricity, degree, treewidth or pagenumber bounded by k, and k-inductive graphs) the algorithms require O(k ċ n ċ log n) worst case time. In the case of graphs with n nodes and m arcs k = O(√m); this gives O(√m ċ n ċ log n) worst case time per operation, which is better for a factor of O(√m log n) than recomputing everything from scratch after each update. If we perform also insertions and deletions of arcs, then the above bounds become amortized.