max/edmonds-matching-algorithm
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

split into separate methods and use noinline attribute to profile

Browse Source
This commit is contained in:
Maximilian Keßler 2023-11-06 12:28:57 +01:00
parent 03f9afa67b
commit f3240b7f6b
Signed by: max
GPG Key ID: BCC5A619923C0BA5
1 changed files with 111 additions and 97 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

208
src/edmonds.cpp
View File

@ -64,6 +64,7 @@ void check_integrity(Graph const & graph)
* @note This assumes that the values of μ, φ and ρ represent a special
* blossom forest on the graph when this method is called.
* **/
__attribute__((noinline))
std::vector<NodeId> path_to_forest_root(Graph const & graph, NodeId id)
{
std::vector<NodeId> retval;
@ -96,6 +97,114 @@ void collect_exposed_vertices(Graph & graph, std::stack<NodeId> & container)
}
}
__attribute__((noinline))
void augment(Graph & graph, std::vector<NodeId> const & x_path, std::vector<NodeId> const & y_path,
std::stack<NodeId> & outer_unvisited_nodes)
{
//std::cout << "Augment" << std::endl;
// Paths are disjoint -> augment
graph.node(x_path.front()).matched_neighbor = y_path.front();
graph.node(y_path.front()).matched_neighbor = x_path.front();
// TODO: put this into own method?
for(size_t i = 1; i < x_path.size(); i += 2)
{
graph.node(x_path[i]).matched_neighbor = x_path[i+1];
graph.node(x_path[i+1]).matched_neighbor = x_path[i];
}
for(size_t i = 1; i < y_path.size(); i += 2)
{
graph.node(y_path[i]).matched_neighbor = y_path[i+1];
graph.node(y_path[i+1]).matched_neighbor = y_path[i];
}
// Note that since this is tail-recursion, this will not generate
// new stack frames in OPT mode
graph.reset_forest();
collect_exposed_vertices(graph, outer_unvisited_nodes);
}
void contract_blossom(Graph & graph, std::vector<NodeId> const & x_path, std::vector<NodeId> const & y_path,
std::stack<NodeId> & outer_unvisited_nodes)
{
//std::cout << "Contract blossom" << std::endl;
// Paths are not disjoint -> shrink blossom
size_t distance_from_x = x_path.size() - 1;
size_t distance_from_y = y_path.size() - 1;
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_y;
}
// found first vertex of x_path \cap y_path
while (graph.rho(x_path[distance_from_x]) != x_path[distance_from_x])
{
++distance_from_x;
++distance_from_y;
};
// found first vertex fixed by rho
NodeId blossom_root_id = x_path[distance_from_x];
// Update φ along the paths to encode the ear decomposition
for (size_t i = 1; i <= distance_from_x; i += 2)
{
if (graph.rho(graph.phi(x_path[i])) != blossom_root_id)
{
graph.node(graph.phi(x_path[i])).phi = x_path[i];
}
}
for (size_t i = 1; i <= distance_from_y; i += 2)
{
if (graph.rho(graph.phi(y_path[i])) != blossom_root_id)
{
graph.node(graph.phi(y_path[i])).phi = y_path[i];
}
}
// Link x and y
if (graph.rho(x_path.front()) != blossom_root_id)
{
graph.node(x_path.front()).phi = y_path.front();
}
if (graph.rho(y_path.front()) != blossom_root_id)
{
graph.node(y_path.front()).phi = x_path.front();
}
// Update root indices. We have to do this for all vertices v with
// ρ(v) in the paths from x or y to r
// We update ρ(v) first for the paths themselves, and then 'contract' ρ
// by updating ρ(v) to r for all vertices where ρ(ρ(v)) = r
// Also, while walking along the paths, we can add all vertices (which are now outer)
// to the stack.
for (size_t i = 0; i <= distance_from_x; ++i)
{
graph.node(x_path[i]).rho = blossom_root_id;
if (not graph.node(x_path[i]).scanned)
{
outer_unvisited_nodes.push(x_path[i]);
}
}
for (size_t i = 0; i <= distance_from_y; ++i)
{
graph.node(y_path[i]).rho = blossom_root_id;
if (not graph.node(y_path[i]).scanned)
{
outer_unvisited_nodes.push(y_path[i]);
}
}
// Iterating over whole graph.
for (NodeId node_id = 0; node_id < graph.num_nodes(); ++node_id)
{
if (graph.rho(graph.rho(node_id)) == blossom_root_id)
{
graph.node(node_id).rho = blossom_root_id;
}
}
//check_integrity(graph);
}
void maximum_matching_from_initial_matching(Graph & graph)
{
graph.reset_forest();
@ -131,107 +240,12 @@ void maximum_matching_from_initial_matching(Graph & graph)
if (x_path.back() != y_path.back())
{
//std::cout << "Augment" << std::endl;
// Paths are disjoint -> augment
graph.node(x_path.front()).matched_neighbor = y_path.front();
graph.node(y_path.front()).matched_neighbor = x_path.front();
// TODO: put this into own method?
for(size_t i = 1; i < x_path.size(); i += 2)
{
graph.node(x_path[i]).matched_neighbor = x_path[i+1];
graph.node(x_path[i+1]).matched_neighbor = x_path[i];
}
for(size_t i = 1; i < y_path.size(); i += 2)
{
graph.node(y_path[i]).matched_neighbor = y_path[i+1];
graph.node(y_path[i+1]).matched_neighbor = y_path[i];
}
// Note that since this is tail-recursion, this will not generate
// new stack frames in OPT mode
graph.reset_forest();
collect_exposed_vertices(graph, outer_unvisited_nodes);
augment(graph, x_path, y_path, outer_unvisited_nodes);
break;
}
else
{
//std::cout << "Contract blossom" << std::endl;
// Paths are not disjoint -> shrink blossom
size_t distance_from_x = x_path.size() - 1;
size_t distance_from_y = y_path.size() - 1;
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_y;
}
// found first vertex of x_path \cap y_path
while (graph.rho(x_path[distance_from_x]) != x_path[distance_from_x])
{
++distance_from_x;
++distance_from_y;
};
// found first vertex fixed by rho
NodeId blossom_root_id = x_path[distance_from_x];
// Update φ along the paths to encode the ear decomposition
for(size_t i = 1; i <= distance_from_x; i += 2)
{
if (graph.rho(graph.phi(x_path[i])) != blossom_root_id)
{
graph.node(graph.phi(x_path[i])).phi = x_path[i];
}
}
for(size_t i = 1; i <= distance_from_y; i += 2)
{
if (graph.rho(graph.phi(y_path[i])) != blossom_root_id)
{
graph.node(graph.phi(y_path[i])).phi = y_path[i];
}
}
// Link x and y
if (graph.rho(x_path.front()) != blossom_root_id)
{
graph.node(x_path.front()).phi = y_path.front();
}
if (graph.rho(y_path.front()) != blossom_root_id)
{
graph.node(y_path.front()).phi = x_path.front();
}
// Update root indices. We have to do this for all vertices v with
// ρ(v) in the paths from x or y to r
// We update ρ(v) first for the paths themselves, and then 'contract' ρ
// by updating ρ(v) to r for all vertices where ρ(ρ(v)) = r
// Also, while walking along the paths, we can add all vertices (which are now outer)
// to the stack.
for(size_t i = 0; i <= distance_from_x; ++i)
{
graph.node(x_path[i]).rho = blossom_root_id;
if(not graph.node(x_path[i]).scanned)
{
outer_unvisited_nodes.push(x_path[i]);
}
}
for(size_t i = 0; i <= distance_from_y; ++i)
{
graph.node(y_path[i]).rho = blossom_root_id;
if(not graph.node(y_path[i]).scanned)
{
outer_unvisited_nodes.push(y_path[i]);
}
}
// Iterating over whole graph.
for(NodeId node_id = 0; node_id < graph.num_nodes(); ++node_id)
{
if (graph.rho(graph.rho(node_id)) == blossom_root_id)
{
graph.node(node_id).rho = blossom_root_id;
}
}
//check_integrity(graph);
contract_blossom(graph, x_path, y_path, outer_unvisited_nodes);
}
}
}