max/edmonds-matching-algorithm
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shrink: bug fixes

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Maximilian Keßler 2023-11-04 20:08:55 +01:00
parent c162b92e8c
commit bfcf885e8f
Signed by: max
GPG Key ID: BCC5A619923C0BA5
1 changed files with 23 additions and 12 deletions
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edmonds.cpp
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@ -77,43 +77,54 @@ Graph maximum_matching_from_initial_matching(Graph & graph)
// Paths are not disjoint -> shrink blossom // Paths are not disjoint -> shrink blossom
size_t distance_from_x = x_path.size() - 1; size_t distance_from_x = x_path.size() - 1;
size_t distance_from_y = y_path.size() - 1; size_t distance_from_y = y_path.size() - 1;
while (x_path[distance_from_x] == y_path[distance_from_y]) while (distance_from_x > 0 and distance_from_y > 0 and \
x_path[distance_from_x - 1] == y_path[distance_from_y - 1])
{ {
--distance_from_x; --distance_from_x;
--distance_from_y; --distance_from_y;
} }
// found first vertex of x_path \cap y_path // found first vertex of x_path \cap y_path
do while (graph.root_of_ear_component(x_path[distance_from_x]) != x_path[distance_from_x])
{ {
++distance_from_x; ++distance_from_x;
++distance_from_y; ++distance_from_y;
} while (graph.root_of_ear_component(x_path[distance_from_x] != x_path[distance_from_x])); };
// found first vertex fixed by root_of_ear_component // found first vertex fixed by root_of_ear_component
size_t x_position_of_blossom_root = distance_from_x + 1; NodeId const blossom = x_path[distance_from_x];
size_t y_position_of_blossom_root = distance_from_y + 1;
NodeId blossom_root = x_path[x_position_of_blossom_root]; NodeId blossom_root_id = x_path[distance_from_x];
for(size_t i = 1; i <= x_position_of_blossom_root; i += 2) for(size_t i = 1; i <= distance_from_x; i += 2)
{ {
if (graph.root_of_ear_component(graph.ear_or_root_neighbor(x_path[i])) != x_path[i]) if (graph.root_of_ear_component(graph.ear_or_root_neighbor(x_path[i])) != blossom_root_id)
{ {
graph.node(graph.ear_or_root_neighbor(x_path[i])).ear_or_root_neighbor = x_path[i]; graph.node(graph.ear_or_root_neighbor(x_path[i])).ear_or_root_neighbor = x_path[i];
} }
} }
for(size_t i = 1; i <= y_position_of_blossom_root; i += 2) for(size_t i = 1; i <= distance_from_y; i += 2)
{ {
if (graph.root_of_ear_component(graph.ear_or_root_neighbor(y_path[i])) != y_path[i]) if (graph.root_of_ear_component(graph.ear_or_root_neighbor(y_path[i])) != blossom_root_id)
{ {
graph.node(graph.ear_or_root_neighbor(y_path[i])).ear_or_root_neighbor = y_path[i]; graph.node(graph.ear_or_root_neighbor(y_path[i])).ear_or_root_neighbor = y_path[i];
} }
} }
if (graph.root_of_ear_component(x_path.front()) != blossom_root) if (graph.root_of_ear_component(x_path.front()) != blossom_root_id)
{ {
graph.node(x_path.front()).ear_or_root_neighbor = y_path.front(); graph.node(x_path.front()).ear_or_root_neighbor = y_path.front();
} }
if (graph.root_of_ear_component(y_path.front()) != blossom_root) if (graph.root_of_ear_component(y_path.front()) != blossom_root_id)
{ {
graph.node(x_path.front()).ear_or_root_neighbor = x_path.front(); graph.node(x_path.front()).ear_or_root_neighbor = x_path.front();
} }
// Update root indices
for(size_t i = 0; i <= distance_from_x; ++i)
{
graph.node(x_path[i]).root_of_ear_component = blossom_root_id;
}
for(size_t i = 0; i <= distance_from_y; ++i)
{
graph.node(y_path[i]).root_of_ear_component = blossom_root_id;
}
} }
} }
} }