We consider a shortest path problem for a directed graph with edges labeled with a cost and a capacity. The problem is to push an unsplittable flow $f$ from a specified source to all other vertices with the minimum cost for all f values. Let G = (V, E) with |V| = n and |E| = m. If there are t different capacity values, we can solve the single source shortest path problem t times for all f in O(tm + tn log n) time, which is O(m^2) when t = m. We improve this time to O(min{t, cn}m + cn^2), which is less than O(cmn) if edge costs are non-negative integers bounded by c. Our algorithm performs better for denser graphs.
@InProceedings{takaoka:OASIcs.ATMOS.2015.56, author = {Takaoka, Tadao}, title = {{Single Source Shortest Paths for All Flows with Integer Costs}}, booktitle = {15th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems (ATMOS 2015)}, pages = {56--67}, series = {Open Access Series in Informatics (OASIcs)}, ISBN = {978-3-939897-99-6}, ISSN = {2190-6807}, year = {2015}, volume = {48}, editor = {Italiano, Giuseppe F. and Schmidt, Marie}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.ATMOS.2015.56}, URN = {urn:nbn:de:0030-drops-54611}, doi = {10.4230/OASIcs.ATMOS.2015.56}, annote = {Keywords: information sharing, shortest path problem for all flows, priority queue, limited edge cost, transportation network} }
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