/usr/include/polymake/graph/diameter.h is in libpolymake-dev-common 3.2r2-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 | /* Copyright (c) 1997-2018
Ewgenij Gawrilow, Michael Joswig (Technische Universitaet Berlin, Germany)
http://www.polymake.org
This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2, or (at your option) any
later version: http://www.gnu.org/licenses/gpl.txt.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
--------------------------------------------------------------------------------
*/
#ifndef POLYMAKE_GRAPH_DIAMETER_H
#define POLYMAKE_GRAPH_DIAMETER_H
#include "polymake/GenericGraph.h"
#include "polymake/graph/graph_iterators.h"
namespace polymake { namespace graph {
class NodeDistances {
protected:
std::vector<int> dist;
public:
static const bool visit_all_edges=false;
NodeDistances() {}
template <typename TGraph>
explicit NodeDistances(const GenericGraph<TGraph>& G)
: dist(G.top().dim(), -1) {}
template <typename TGraph>
void clear(const GenericGraph<TGraph>& G)
{
std::fill(dist.begin(), dist.end(), -1);
}
bool operator()(int n)
{
dist[n]=0;
return true;
}
bool operator()(int n_from, int n_to)
{
if (dist[n_to]<0) {
dist[n_to]=dist[n_from]+1;
return true;
}
return false;
}
int operator[] (int n) const { return dist[n]; }
};
/// Determine the diameter of a graph.
template <typename TGraph>
int diameter(const GenericGraph<TGraph>& G)
{
BFSiterator<TGraph, VisitorTag<NodeDistances>> it(G);
int diam=0;
for (auto n=entire(nodes(G)); !n.at_end(); ++n) {
for (it.reset(*n); it.undiscovered_nodes()>0; ++it) ;
assign_max(diam, it.node_visitor()[it.get_queue().back()]);
}
return diam;
}
} }
#endif // POLYMAKE_GRAPH_DIAMETER_H
// Local Variables:
// mode:C++
// c-basic-offset:3
// indent-tabs-mode:nil
// End:
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