/usr/include/polymake/graph/bipartite.tcc 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 83 84 85 86 87 88 89 90 91 92 | /* 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.
--------------------------------------------------------------------------------
*/
#include "polymake/graph/graph_iterators.h"
#include "polymake/graph/bipartite.h"
#include "polymake/graph/connected.h"
#include <cstdlib>
namespace polymake { namespace graph {
class BipartiteColoring {
protected:
std::vector<int> color;
int sign;
public:
static const bool visit_all_edges=true;
BipartiteColoring();
template <typename TGraph>
explicit BipartiteColoring(const GenericGraph<TGraph>& G)
: color(G.top().dim(), 0)
, sign(0)
{}
template <typename TGraph>
void clear(const GenericGraph<TGraph>& G)
{
std::fill(color.begin(), color.end(), 0);
sign=0;
}
bool operator()(int n)
{
color[n]=1;
sign=1;
return true;
}
bool operator()(int n_from, int n_to)
{
if (color[n_to]==0) {
sign += color[n_to]=-color[n_from];
return true;
} else if (color[n_to]==color[n_from]) {
throw n_to;
} else {
return false;
}
}
int get_sign() const { return std::abs(sign); }
int get_color(int n) const { return color[n]; }
};
template <typename TGraph>
int bipartite_sign(const GenericGraph<TGraph,Undirected>& G)
{
int signature=0;
for (connected_components_iterator<TGraph> C(G); !C.at_end(); ++C) {
int this_node=C->front();
BFSiterator<TGraph, VisitorTag<BipartiteColoring> > it(G, this_node);
try {
while (!it.at_end()) ++it;
} catch (int) {
return -1;
}
signature += it.node_visitor().get_sign();
}
return signature;
}
} }
// Local Variables:
// mode:C++
// c-basic-offset:3
// indent-tabs-mode:nil
// End:
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