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// (C) Copyright Jeremy Siek 2004
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
#ifndef BOOST_DETAIL_DISJOINT_SETS_HPP
#define BOOST_DETAIL_DISJOINT_SETS_HPP
namespace boost {
namespace detail {
template <class ParentPA, class Vertex>
Vertex
find_representative_with_path_halving(ParentPA p, Vertex v)
{
Vertex parent = get(p, v);
Vertex grandparent = get(p, parent);
while (parent != grandparent) {
put(p, v, grandparent);
v = grandparent;
parent = get(p, v);
grandparent = get(p, parent);
}
return parent;
}
template <class ParentPA, class Vertex>
Vertex
find_representative_with_full_compression(ParentPA parent, Vertex v)
{
Vertex old = v;
Vertex ancestor = get(parent, v);
while (ancestor != v) {
v = ancestor;
ancestor = get(parent, v);
}
v = get(parent, old);
while (ancestor != v) {
put(parent, old, ancestor);
old = v;
v = get(parent, old);
}
return ancestor;
}
/* the postcondition of link sets is:
component_representative(i) == component_representative(j)
*/
template <class ParentPA, class RankPA, class Vertex,
class ComponentRepresentative>
inline void
link_sets(ParentPA p, RankPA rank, Vertex i, Vertex j,
ComponentRepresentative comp_rep)
{
i = comp_rep(p, i);
j = comp_rep(p, j);
if (i == j) return;
if (get(rank, i) > get(rank, j))
put(p, j, i);
else {
put(p, i, j);
if (get(rank, i) == get(rank, j))
put(rank, j, get(rank, j) + 1);
}
}
// normalize components has the following postcondidition:
// i >= p[i]
// that is, the representative is the node with the smallest index in its class
// as its precondition it it assumes that the node container is compressed
template <class ParentPA, class Vertex>
inline void
normalize_node(ParentPA p, Vertex i)
{
if (i > get(p,i) || get(p, get(p,i)) != get(p,i))
put(p,i, get(p, get(p,i)));
else {
put(p, get(p,i), i);
put(p, i, i);
}
}
} // namespace detail
} // namespace boost
#endif // BOOST_DETAIL_DISJOINT_SETS_HPP
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