boost/graph/boykov_kolmogorov_max_flow.hpp
// Copyright (c) 2006, Stephan Diederich
//
// This code may be used under either of the following two licences:
//
// Permission is hereby granted, free of charge, to any person
// obtaining a copy of this software and associated documentation
// files (the "Software"), to deal in the Software without
// restriction, including without limitation the rights to use,
// copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following
// conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
// OTHER DEALINGS IN THE SOFTWARE. OF SUCH DAMAGE.
//
// Or:
//
// 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_BOYKOV_KOLMOGOROV_MAX_FLOW_HPP
#define BOOST_BOYKOV_KOLMOGOROV_MAX_FLOW_HPP
#include <boost/config.hpp>
#include <boost/assert.hpp>
#include <vector>
#include <list>
#include <utility>
#include <iosfwd>
#include <algorithm> // for std::min and std::max
#include <boost/pending/queue.hpp>
#include <boost/limits.hpp>
#include <boost/property_map/property_map.hpp>
#include <boost/none_t.hpp>
#include <boost/graph/graph_concepts.hpp>
#include <boost/graph/named_function_params.hpp>
#include <boost/graph/lookup_edge.hpp>
#include <boost/concept/assert.hpp>
// The algorithm impelemented here is described in:
//
// Boykov, Y., Kolmogorov, V. "An Experimental Comparison of Min-Cut/Max-Flow
// Algorithms for Energy Minimization in Vision", In IEEE Transactions on
// Pattern Analysis and Machine Intelligence, vol. 26, no. 9, pp. 1124-1137,
// Sep 2004.
//
// For further reading, also see:
//
// Kolmogorov, V. "Graph Based Algorithms for Scene Reconstruction from Two or
// More Views". PhD thesis, Cornell University, Sep 2003.
namespace boost {
namespace detail {
template <class Graph,
class EdgeCapacityMap,
class ResidualCapacityEdgeMap,
class ReverseEdgeMap,
class PredecessorMap,
class ColorMap,
class DistanceMap,
class IndexMap>
class bk_max_flow {
typedef typename property_traits<EdgeCapacityMap>::value_type tEdgeVal;
typedef graph_traits<Graph> tGraphTraits;
typedef typename tGraphTraits::vertex_iterator vertex_iterator;
typedef typename tGraphTraits::vertex_descriptor vertex_descriptor;
typedef typename tGraphTraits::edge_descriptor edge_descriptor;
typedef typename tGraphTraits::edge_iterator edge_iterator;
typedef typename tGraphTraits::out_edge_iterator out_edge_iterator;
typedef boost::queue<vertex_descriptor> tQueue; //queue of vertices, used in adoption-stage
typedef typename property_traits<ColorMap>::value_type tColorValue;
typedef color_traits<tColorValue> tColorTraits;
typedef typename property_traits<DistanceMap>::value_type tDistanceVal;
public:
bk_max_flow(Graph& g,
EdgeCapacityMap cap,
ResidualCapacityEdgeMap res,
ReverseEdgeMap rev,
PredecessorMap pre,
ColorMap color,
DistanceMap dist,
IndexMap idx,
vertex_descriptor src,
vertex_descriptor sink):
m_g(g),
m_index_map(idx),
m_cap_map(cap),
m_res_cap_map(res),
m_rev_edge_map(rev),
m_pre_map(pre),
m_tree_map(color),
m_dist_map(dist),
m_source(src),
m_sink(sink),
m_active_nodes(),
m_in_active_list_vec(num_vertices(g), false),
m_in_active_list_map(make_iterator_property_map(m_in_active_list_vec.begin(), m_index_map)),
m_has_parent_vec(num_vertices(g), false),
m_has_parent_map(make_iterator_property_map(m_has_parent_vec.begin(), m_index_map)),
m_time_vec(num_vertices(g), 0),
m_time_map(make_iterator_property_map(m_time_vec.begin(), m_index_map)),
m_flow(0),
m_time(1),
m_last_grow_vertex(graph_traits<Graph>::null_vertex()){
// initialize the color-map with gray-values
vertex_iterator vi, v_end;
for(boost::tie(vi, v_end) = vertices(m_g); vi != v_end; ++vi){
set_tree(*vi, tColorTraits::gray());
}
// Initialize flow to zero which means initializing
// the residual capacity equal to the capacity
edge_iterator ei, e_end;
for(boost::tie(ei, e_end) = edges(m_g); ei != e_end; ++ei) {
put(m_res_cap_map, *ei, get(m_cap_map, *ei));
BOOST_ASSERT(get(m_rev_edge_map, get(m_rev_edge_map, *ei)) == *ei); //check if the reverse edge map is build up properly
}
//init the search trees with the two terminals
set_tree(m_source, tColorTraits::black());
set_tree(m_sink, tColorTraits::white());
put(m_time_map, m_source, 1);
put(m_time_map, m_sink, 1);
}
tEdgeVal max_flow(){
//augment direct paths from SOURCE->SINK and SOURCE->VERTEX->SINK
augment_direct_paths();
//start the main-loop
while(true){
bool path_found;
edge_descriptor connecting_edge;
boost::tie(connecting_edge, path_found) = grow(); //find a path from source to sink
if(!path_found){
//we're finished, no more paths were found
break;
}
++m_time;
augment(connecting_edge); //augment that path
adopt(); //rebuild search tree structure
}
return m_flow;
}
// the complete class is protected, as we want access to members in
// derived test-class (see test/boykov_kolmogorov_max_flow_test.cpp)
protected:
void augment_direct_paths(){
// in a first step, we augment all direct paths from source->NODE->sink
// and additionally paths from source->sink. This improves especially
// graphcuts for segmentation, as most of the nodes have source/sink
// connects but shouldn't have an impact on other maxflow problems
// (this is done in grow() anyway)
out_edge_iterator ei, e_end;
for(boost::tie(ei, e_end) = out_edges(m_source, m_g); ei != e_end; ++ei){
edge_descriptor from_source = *ei;
vertex_descriptor current_node = target(from_source, m_g);
if(current_node == m_sink){
tEdgeVal cap = get(m_res_cap_map, from_source);
put(m_res_cap_map, from_source, 0);
m_flow += cap;
continue;
}
edge_descriptor to_sink;
bool is_there;
boost::tie(to_sink, is_there) = lookup_edge(current_node, m_sink, m_g);
if(is_there){
tEdgeVal cap_from_source = get(m_res_cap_map, from_source);
tEdgeVal cap_to_sink = get(m_res_cap_map, to_sink);
if(cap_from_source > cap_to_sink){
set_tree(current_node, tColorTraits::black());
add_active_node(current_node);
set_edge_to_parent(current_node, from_source);
put(m_dist_map, current_node, 1);
put(m_time_map, current_node, 1);
// add stuff to flow and update residuals. we dont need to
// update reverse_edges, as incoming/outgoing edges to/from
// source/sink don't count for max-flow
put(m_res_cap_map, from_source, get(m_res_cap_map, from_source) - cap_to_sink);
put(m_res_cap_map, to_sink, 0);
m_flow += cap_to_sink;
} else if(cap_to_sink > 0){
set_tree(current_node, tColorTraits::white());
add_active_node(current_node);
set_edge_to_parent(current_node, to_sink);
put(m_dist_map, current_node, 1);
put(m_time_map, current_node, 1);
// add stuff to flow and update residuals. we dont need to update
// reverse_edges, as incoming/outgoing edges to/from source/sink
// don't count for max-flow
put(m_res_cap_map, to_sink, get(m_res_cap_map, to_sink) - cap_from_source);
put(m_res_cap_map, from_source, 0);
m_flow += cap_from_source;
}
} else if(get(m_res_cap_map, from_source)){
// there is no sink connect, so we can't augment this path, but to
// avoid adding m_source to the active nodes, we just activate this
// node and set the approciate things
set_tree(current_node, tColorTraits::black());
set_edge_to_parent(current_node, from_source);
put(m_dist_map, current_node, 1);
put(m_time_map, current_node, 1);
add_active_node(current_node);
}
}
for(boost::tie(ei, e_end) = out_edges(m_sink, m_g); ei != e_end; ++ei){
edge_descriptor to_sink = get(m_rev_edge_map, *ei);
vertex_descriptor current_node = source(to_sink, m_g);
if(get(m_res_cap_map, to_sink)){
set_tree(current_node, tColorTraits::white());
set_edge_to_parent(current_node, to_sink);
put(m_dist_map, current_node, 1);
put(m_time_map, current_node, 1);
add_active_node(current_node);
}
}
}
/**
* Returns a pair of an edge and a boolean. if the bool is true, the
* edge is a connection of a found path from s->t , read "the link" and
* source(returnVal, m_g) is the end of the path found in the source-tree
* target(returnVal, m_g) is the beginning of the path found in the sink-tree
*/
std::pair<edge_descriptor, bool> grow(){
BOOST_ASSERT(m_orphans.empty());
vertex_descriptor current_node;
while((current_node = get_next_active_node()) != graph_traits<Graph>::null_vertex()){ //if there is one
BOOST_ASSERT(get_tree(current_node) != tColorTraits::gray() &&
(has_parent(current_node) ||
current_node == m_source ||
current_node == m_sink));
if(get_tree(current_node) == tColorTraits::black()){
//source tree growing
out_edge_iterator ei, e_end;
if(current_node != m_last_grow_vertex){
m_last_grow_vertex = current_node;
boost::tie(m_last_grow_edge_it, m_last_grow_edge_end) = out_edges(current_node, m_g);
}
for(; m_last_grow_edge_it != m_last_grow_edge_end; ++m_last_grow_edge_it) {
edge_descriptor out_edge = *m_last_grow_edge_it;
if(get(m_res_cap_map, out_edge) > 0){ //check if we have capacity left on this edge
vertex_descriptor other_node = target(out_edge, m_g);
if(get_tree(other_node) == tColorTraits::gray()){ //it's a free node
set_tree(other_node, tColorTraits::black()); //aquire other node to our search tree
set_edge_to_parent(other_node, out_edge); //set us as parent
put(m_dist_map, other_node, get(m_dist_map, current_node) + 1); //and update the distance-heuristic
put(m_time_map, other_node, get(m_time_map, current_node));
add_active_node(other_node);
} else if(get_tree(other_node) == tColorTraits::black()) {
// we do this to get shorter paths. check if we are nearer to
// the source as its parent is
if(is_closer_to_terminal(current_node, other_node)){
set_edge_to_parent(other_node, out_edge);
put(m_dist_map, other_node, get(m_dist_map, current_node) + 1);
put(m_time_map, other_node, get(m_time_map, current_node));
}
} else{
BOOST_ASSERT(get_tree(other_node)==tColorTraits::white());
//kewl, found a path from one to the other search tree, return
// the connecting edge in src->sink dir
return std::make_pair(out_edge, true);
}
}
} //for all out-edges
} //source-tree-growing
else{
BOOST_ASSERT(get_tree(current_node) == tColorTraits::white());
out_edge_iterator ei, e_end;
if(current_node != m_last_grow_vertex){
m_last_grow_vertex = current_node;
boost::tie(m_last_grow_edge_it, m_last_grow_edge_end) = out_edges(current_node, m_g);
}
for(; m_last_grow_edge_it != m_last_grow_edge_end; ++m_last_grow_edge_it){
edge_descriptor in_edge = get(m_rev_edge_map, *m_last_grow_edge_it);
if(get(m_res_cap_map, in_edge) > 0){ //check if there is capacity left
vertex_descriptor other_node = source(in_edge, m_g);
if(get_tree(other_node) == tColorTraits::gray()){ //it's a free node
set_tree(other_node, tColorTraits::white()); //aquire that node to our search tree
set_edge_to_parent(other_node, in_edge); //set us as parent
add_active_node(other_node); //activate that node
put(m_dist_map, other_node, get(m_dist_map, current_node) + 1); //set its distance
put(m_time_map, other_node, get(m_time_map, current_node));//and time
} else if(get_tree(other_node) == tColorTraits::white()){
if(is_closer_to_terminal(current_node, other_node)){
//we are closer to the sink than its parent is, so we "adopt" him
set_edge_to_parent(other_node, in_edge);
put(m_dist_map, other_node, get(m_dist_map, current_node) + 1);
put(m_time_map, other_node, get(m_time_map, current_node));
}
} else{
BOOST_ASSERT(get_tree(other_node)==tColorTraits::black());
//kewl, found a path from one to the other search tree,
// return the connecting edge in src->sink dir
return std::make_pair(in_edge, true);
}
}
} //for all out-edges
} //sink-tree growing
//all edges of that node are processed, and no more paths were found.
// remove if from the front of the active queue
finish_node(current_node);
} //while active_nodes not empty
//no active nodes anymore and no path found, we're done
return std::make_pair(edge_descriptor(), false);
}
/**
* augments path from s->t and updates residual graph
* source(e, m_g) is the end of the path found in the source-tree
* target(e, m_g) is the beginning of the path found in the sink-tree
* this phase generates orphans on satured edges, if the attached verts are
* from different search-trees orphans are ordered in distance to
* sink/source. first the farest from the source are front_inserted into
* the orphans list, and after that the sink-tree-orphans are
* front_inserted. when going to adoption stage the orphans are popped_front,
* and so we process the nearest verts to the terminals first
*/
void augment(edge_descriptor e) {
BOOST_ASSERT(get_tree(target(e, m_g)) == tColorTraits::white());
BOOST_ASSERT(get_tree(source(e, m_g)) == tColorTraits::black());
BOOST_ASSERT(m_orphans.empty());
const tEdgeVal bottleneck = find_bottleneck(e);
//now we push the found flow through the path
//for each edge we saturate we have to look for the verts that belong to that edge, one of them becomes an orphans
//now process the connecting edge
put(m_res_cap_map, e, get(m_res_cap_map, e) - bottleneck);
BOOST_ASSERT(get(m_res_cap_map, e) >= 0);
put(m_res_cap_map, get(m_rev_edge_map, e), get(m_res_cap_map, get(m_rev_edge_map, e)) + bottleneck);
//now we follow the path back to the source
vertex_descriptor current_node = source(e, m_g);
while(current_node != m_source){
edge_descriptor pred = get_edge_to_parent(current_node);
put(m_res_cap_map, pred, get(m_res_cap_map, pred) - bottleneck);
BOOST_ASSERT(get(m_res_cap_map, pred) >= 0);
put(m_res_cap_map, get(m_rev_edge_map, pred), get(m_res_cap_map, get(m_rev_edge_map, pred)) + bottleneck);
if(get(m_res_cap_map, pred) == 0){
set_no_parent(current_node);
m_orphans.push_front(current_node);
}
current_node = source(pred, m_g);
}
//then go forward in the sink-tree
current_node = target(e, m_g);
while(current_node != m_sink){
edge_descriptor pred = get_edge_to_parent(current_node);
put(m_res_cap_map, pred, get(m_res_cap_map, pred) - bottleneck);
BOOST_ASSERT(get(m_res_cap_map, pred) >= 0);
put(m_res_cap_map, get(m_rev_edge_map, pred), get(m_res_cap_map, get(m_rev_edge_map, pred)) + bottleneck);
if(get(m_res_cap_map, pred) == 0){
set_no_parent(current_node);
m_orphans.push_front(current_node);
}
current_node = target(pred, m_g);
}
//and add it to the max-flow
m_flow += bottleneck;
}
/**
* returns the bottleneck of a s->t path (end_of_path is last vertex in
* source-tree, begin_of_path is first vertex in sink-tree)
*/
inline tEdgeVal find_bottleneck(edge_descriptor e){
BOOST_USING_STD_MIN();
tEdgeVal minimum_cap = get(m_res_cap_map, e);
vertex_descriptor current_node = source(e, m_g);
//first go back in the source tree
while(current_node != m_source){
edge_descriptor pred = get_edge_to_parent(current_node);
minimum_cap = min BOOST_PREVENT_MACRO_SUBSTITUTION(minimum_cap, get(m_res_cap_map, pred));
current_node = source(pred, m_g);
}
//then go forward in the sink-tree
current_node = target(e, m_g);
while(current_node != m_sink){
edge_descriptor pred = get_edge_to_parent(current_node);
minimum_cap = min BOOST_PREVENT_MACRO_SUBSTITUTION(minimum_cap, get(m_res_cap_map, pred));
current_node = target(pred, m_g);
}
return minimum_cap;
}
/**
* rebuild search trees
* empty the queue of orphans, and find new parents for them or just drop
* them from the search trees
*/
void adopt(){
while(!m_orphans.empty() || !m_child_orphans.empty()){
vertex_descriptor current_node;
if(m_child_orphans.empty()){
//get the next orphan from the main-queue and remove it
current_node = m_orphans.front();
m_orphans.pop_front();
} else{
current_node = m_child_orphans.front();
m_child_orphans.pop();
}
if(get_tree(current_node) == tColorTraits::black()){
//we're in the source-tree
tDistanceVal min_distance = (std::numeric_limits<tDistanceVal>::max)();
edge_descriptor new_parent_edge;
out_edge_iterator ei, e_end;
for(boost::tie(ei, e_end) = out_edges(current_node, m_g); ei != e_end; ++ei){
const edge_descriptor in_edge = get(m_rev_edge_map, *ei);
BOOST_ASSERT(target(in_edge, m_g) == current_node); //we should be the target of this edge
if(get(m_res_cap_map, in_edge) > 0){
vertex_descriptor other_node = source(in_edge, m_g);
if(get_tree(other_node) == tColorTraits::black() && has_source_connect(other_node)){
if(get(m_dist_map, other_node) < min_distance){
min_distance = get(m_dist_map, other_node);
new_parent_edge = in_edge;
}
}
}
}
if(min_distance != (std::numeric_limits<tDistanceVal>::max)()){
set_edge_to_parent(current_node, new_parent_edge);
put(m_dist_map, current_node, min_distance + 1);
put(m_time_map, current_node, m_time);
} else{
put(m_time_map, current_node, 0);
for(boost::tie(ei, e_end) = out_edges(current_node, m_g); ei != e_end; ++ei){
edge_descriptor in_edge = get(m_rev_edge_map, *ei);
vertex_descriptor other_node = source(in_edge, m_g);
if(get_tree(other_node) == tColorTraits::black() && other_node != m_source){
if(get(m_res_cap_map, in_edge) > 0){
add_active_node(other_node);
}
if(has_parent(other_node) && source(get_edge_to_parent(other_node), m_g) == current_node){
//we are the parent of that node
//it has to find a new parent, too
set_no_parent(other_node);
m_child_orphans.push(other_node);
}
}
}
set_tree(current_node, tColorTraits::gray());
} //no parent found
} //source-tree-adoption
else{
//now we should be in the sink-tree, check that...
BOOST_ASSERT(get_tree(current_node) == tColorTraits::white());
out_edge_iterator ei, e_end;
edge_descriptor new_parent_edge;
tDistanceVal min_distance = (std::numeric_limits<tDistanceVal>::max)();
for(boost::tie(ei, e_end) = out_edges(current_node, m_g); ei != e_end; ++ei){
const edge_descriptor out_edge = *ei;
if(get(m_res_cap_map, out_edge) > 0){
const vertex_descriptor other_node = target(out_edge, m_g);
if(get_tree(other_node) == tColorTraits::white() && has_sink_connect(other_node))
if(get(m_dist_map, other_node) < min_distance){
min_distance = get(m_dist_map, other_node);
new_parent_edge = out_edge;
}
}
}
if(min_distance != (std::numeric_limits<tDistanceVal>::max)()){
set_edge_to_parent(current_node, new_parent_edge);
put(m_dist_map, current_node, min_distance + 1);
put(m_time_map, current_node, m_time);
} else{
put(m_time_map, current_node, 0);
for(boost::tie(ei, e_end) = out_edges(current_node, m_g); ei != e_end; ++ei){
const edge_descriptor out_edge = *ei;
const vertex_descriptor other_node = target(out_edge, m_g);
if(get_tree(other_node) == tColorTraits::white() && other_node != m_sink){
if(get(m_res_cap_map, out_edge) > 0){
add_active_node(other_node);
}
if(has_parent(other_node) && target(get_edge_to_parent(other_node), m_g) == current_node){
//we were it's parent, so it has to find a new one, too
set_no_parent(other_node);
m_child_orphans.push(other_node);
}
}
}
set_tree(current_node, tColorTraits::gray());
} //no parent found
} //sink-tree adoption
} //while !orphans.empty()
} //adopt
/**
* return next active vertex if there is one, otherwise a null_vertex
*/
inline vertex_descriptor get_next_active_node(){
while(true){
if(m_active_nodes.empty())
return graph_traits<Graph>::null_vertex();
vertex_descriptor v = m_active_nodes.front();
//if it has no parent, this node can't be active (if its not source or sink)
if(!has_parent(v) && v != m_source && v != m_sink){
m_active_nodes.pop();
put(m_in_active_list_map, v, false);
} else{
BOOST_ASSERT(get_tree(v) == tColorTraits::black() || get_tree(v) == tColorTraits::white());
return v;
}
}
}
/**
* adds v as an active vertex, but only if its not in the list already
*/
inline void add_active_node(vertex_descriptor v){
BOOST_ASSERT(get_tree(v) != tColorTraits::gray());
if(get(m_in_active_list_map, v)){
if (m_last_grow_vertex == v) {
m_last_grow_vertex = graph_traits<Graph>::null_vertex();
}
return;
} else{
put(m_in_active_list_map, v, true);
m_active_nodes.push(v);
}
}
/**
* finish_node removes a node from the front of the active queue (its called in grow phase, if no more paths can be found using this node)
*/
inline void finish_node(vertex_descriptor v){
BOOST_ASSERT(m_active_nodes.front() == v);
m_active_nodes.pop();
put(m_in_active_list_map, v, false);
m_last_grow_vertex = graph_traits<Graph>::null_vertex();
}
/**
* removes a vertex from the queue of active nodes (actually this does nothing,
* but checks if this node has no parent edge, as this is the criteria for
* being no more active)
*/
inline void remove_active_node(vertex_descriptor v){
BOOST_ASSERT(!has_parent(v));
}
/**
* returns the search tree of v; tColorValue::black() for source tree,
* white() for sink tree, gray() for no tree
*/
inline tColorValue get_tree(vertex_descriptor v) const {
return get(m_tree_map, v);
}
/**
* sets search tree of v; tColorValue::black() for source tree, white()
* for sink tree, gray() for no tree
*/
inline void set_tree(vertex_descriptor v, tColorValue t){
put(m_tree_map, v, t);
}
/**
* returns edge to parent vertex of v;
*/
inline edge_descriptor get_edge_to_parent(vertex_descriptor v) const{
return get(m_pre_map, v);
}
/**
* returns true if the edge stored in m_pre_map[v] is a valid entry
*/
inline bool has_parent(vertex_descriptor v) const{
return get(m_has_parent_map, v);
}
/**
* sets edge to parent vertex of v;
*/
inline void set_edge_to_parent(vertex_descriptor v, edge_descriptor f_edge_to_parent){
BOOST_ASSERT(get(m_res_cap_map, f_edge_to_parent) > 0);
put(m_pre_map, v, f_edge_to_parent);
put(m_has_parent_map, v, true);
}
/**
* removes the edge to parent of v (this is done by invalidating the
* entry an additional map)
*/
inline void set_no_parent(vertex_descriptor v){
put(m_has_parent_map, v, false);
}
/**
* checks if vertex v has a connect to the sink-vertex (@var m_sink)
* @param v the vertex which is checked
* @return true if a path to the sink was found, false if not
*/
inline bool has_sink_connect(vertex_descriptor v){
tDistanceVal current_distance = 0;
vertex_descriptor current_vertex = v;
while(true){
if(get(m_time_map, current_vertex) == m_time){
//we found a node which was already checked this round. use it for distance calculations
current_distance += get(m_dist_map, current_vertex);
break;
}
if(current_vertex == m_sink){
put(m_time_map, m_sink, m_time);
break;
}
if(has_parent(current_vertex)){
//it has a parent, so get it
current_vertex = target(get_edge_to_parent(current_vertex), m_g);
++current_distance;
} else{
//no path found
return false;
}
}
current_vertex=v;
while(get(m_time_map, current_vertex) != m_time){
put(m_dist_map, current_vertex, current_distance);
--current_distance;
put(m_time_map, current_vertex, m_time);
current_vertex = target(get_edge_to_parent(current_vertex), m_g);
}
return true;
}
/**
* checks if vertex v has a connect to the source-vertex (@var m_source)
* @param v the vertex which is checked
* @return true if a path to the source was found, false if not
*/
inline bool has_source_connect(vertex_descriptor v){
tDistanceVal current_distance = 0;
vertex_descriptor current_vertex = v;
while(true){
if(get(m_time_map, current_vertex) == m_time){
//we found a node which was already checked this round. use it for distance calculations
current_distance += get(m_dist_map, current_vertex);
break;
}
if(current_vertex == m_source){
put(m_time_map, m_source, m_time);
break;
}
if(has_parent(current_vertex)){
//it has a parent, so get it
current_vertex = source(get_edge_to_parent(current_vertex), m_g);
++current_distance;
} else{
//no path found
return false;
}
}
current_vertex=v;
while(get(m_time_map, current_vertex) != m_time){
put(m_dist_map, current_vertex, current_distance);
--current_distance;
put(m_time_map, current_vertex, m_time);
current_vertex = source(get_edge_to_parent(current_vertex), m_g);
}
return true;
}
/**
* returns true, if p is closer to a terminal than q
*/
inline bool is_closer_to_terminal(vertex_descriptor p, vertex_descriptor q){
//checks the timestamps first, to build no cycles, and after that the real distance
return (get(m_time_map, q) <= get(m_time_map, p) &&
get(m_dist_map, q) > get(m_dist_map, p)+1);
}
////////
// member vars
////////
Graph& m_g;
IndexMap m_index_map;
EdgeCapacityMap m_cap_map;
ResidualCapacityEdgeMap m_res_cap_map;
ReverseEdgeMap m_rev_edge_map;
PredecessorMap m_pre_map; //stores paths found in the growth stage
ColorMap m_tree_map; //maps each vertex into one of the two search tree or none (gray())
DistanceMap m_dist_map; //stores distance to source/sink nodes
vertex_descriptor m_source;
vertex_descriptor m_sink;
tQueue m_active_nodes;
std::vector<bool> m_in_active_list_vec;
iterator_property_map<std::vector<bool>::iterator, IndexMap> m_in_active_list_map;
std::list<vertex_descriptor> m_orphans;
tQueue m_child_orphans; // we use a second queuqe for child orphans, as they are FIFO processed
std::vector<bool> m_has_parent_vec;
iterator_property_map<std::vector<bool>::iterator, IndexMap> m_has_parent_map;
std::vector<long> m_time_vec; //timestamp of each node, used for sink/source-path calculations
iterator_property_map<std::vector<long>::iterator, IndexMap> m_time_map;
tEdgeVal m_flow;
long m_time;
vertex_descriptor m_last_grow_vertex;
out_edge_iterator m_last_grow_edge_it;
out_edge_iterator m_last_grow_edge_end;
};
} //namespace boost::detail
/**
* non-named-parameter version, given everything
* this is the catch all version
*/
template<class Graph,
class CapacityEdgeMap,
class ResidualCapacityEdgeMap,
class ReverseEdgeMap, class PredecessorMap,
class ColorMap,
class DistanceMap,
class IndexMap>
typename property_traits<CapacityEdgeMap>::value_type
boykov_kolmogorov_max_flow(Graph& g,
CapacityEdgeMap cap,
ResidualCapacityEdgeMap res_cap,
ReverseEdgeMap rev_map,
PredecessorMap pre_map,
ColorMap color,
DistanceMap dist,
IndexMap idx,
typename graph_traits<Graph>::vertex_descriptor src,
typename graph_traits<Graph>::vertex_descriptor sink)
{
typedef typename graph_traits<Graph>::vertex_descriptor vertex_descriptor;
typedef typename graph_traits<Graph>::edge_descriptor edge_descriptor;
//as this method is the last one before we instantiate the solver, we do the concept checks here
BOOST_CONCEPT_ASSERT(( VertexListGraphConcept<Graph> )); //to have vertices(), num_vertices(),
BOOST_CONCEPT_ASSERT(( EdgeListGraphConcept<Graph> )); //to have edges()
BOOST_CONCEPT_ASSERT(( IncidenceGraphConcept<Graph> )); //to have source(), target() and out_edges()
BOOST_CONCEPT_ASSERT(( ReadablePropertyMapConcept<CapacityEdgeMap, edge_descriptor> )); //read flow-values from edges
BOOST_CONCEPT_ASSERT(( ReadWritePropertyMapConcept<ResidualCapacityEdgeMap, edge_descriptor> )); //write flow-values to residuals
BOOST_CONCEPT_ASSERT(( ReadablePropertyMapConcept<ReverseEdgeMap, edge_descriptor> )); //read out reverse edges
BOOST_CONCEPT_ASSERT(( ReadWritePropertyMapConcept<PredecessorMap, vertex_descriptor> )); //store predecessor there
BOOST_CONCEPT_ASSERT(( ReadWritePropertyMapConcept<ColorMap, vertex_descriptor> )); //write corresponding tree
BOOST_CONCEPT_ASSERT(( ReadWritePropertyMapConcept<DistanceMap, vertex_descriptor> )); //write distance to source/sink
BOOST_CONCEPT_ASSERT(( ReadablePropertyMapConcept<IndexMap, vertex_descriptor> )); //get index 0...|V|-1
BOOST_ASSERT(num_vertices(g) >= 2 && src != sink);
detail::bk_max_flow<
Graph, CapacityEdgeMap, ResidualCapacityEdgeMap, ReverseEdgeMap,
PredecessorMap, ColorMap, DistanceMap, IndexMap
> algo(g, cap, res_cap, rev_map, pre_map, color, dist, idx, src, sink);
return algo.max_flow();
}
/**
* non-named-parameter version, given capacity, residucal_capacity,
* reverse_edges, and an index map.
*/
template<class Graph,
class CapacityEdgeMap,
class ResidualCapacityEdgeMap,
class ReverseEdgeMap,
class IndexMap>
typename property_traits<CapacityEdgeMap>::value_type
boykov_kolmogorov_max_flow(Graph& g,
CapacityEdgeMap cap,
ResidualCapacityEdgeMap res_cap,
ReverseEdgeMap rev,
IndexMap idx,
typename graph_traits<Graph>::vertex_descriptor src,
typename graph_traits<Graph>::vertex_descriptor sink)
{
typename graph_traits<Graph>::vertices_size_type n_verts = num_vertices(g);
std::vector<typename graph_traits<Graph>::edge_descriptor> predecessor_vec(n_verts);
std::vector<default_color_type> color_vec(n_verts);
std::vector<typename graph_traits<Graph>::vertices_size_type> distance_vec(n_verts);
return
boykov_kolmogorov_max_flow(
g, cap, res_cap, rev,
make_iterator_property_map(predecessor_vec.begin(), idx),
make_iterator_property_map(color_vec.begin(), idx),
make_iterator_property_map(distance_vec.begin(), idx),
idx, src, sink);
}
/**
* non-named-parameter version, some given: capacity, residual_capacity,
* reverse_edges, color_map and an index map. Use this if you are interested in
* the minimum cut, as the color map provides that info.
*/
template<class Graph,
class CapacityEdgeMap,
class ResidualCapacityEdgeMap,
class ReverseEdgeMap,
class ColorMap,
class IndexMap>
typename property_traits<CapacityEdgeMap>::value_type
boykov_kolmogorov_max_flow(Graph& g,
CapacityEdgeMap cap,
ResidualCapacityEdgeMap res_cap,
ReverseEdgeMap rev,
ColorMap color,
IndexMap idx,
typename graph_traits<Graph>::vertex_descriptor src,
typename graph_traits<Graph>::vertex_descriptor sink)
{
typename graph_traits<Graph>::vertices_size_type n_verts = num_vertices(g);
std::vector<typename graph_traits<Graph>::edge_descriptor> predecessor_vec(n_verts);
std::vector<typename graph_traits<Graph>::vertices_size_type> distance_vec(n_verts);
return
boykov_kolmogorov_max_flow(
g, cap, res_cap, rev,
make_iterator_property_map(predecessor_vec.begin(), idx),
color,
make_iterator_property_map(distance_vec.begin(), idx),
idx, src, sink);
}
/**
* named-parameter version, some given
*/
template<class Graph, class P, class T, class R>
typename property_traits<typename property_map<Graph, edge_capacity_t>::const_type>::value_type
boykov_kolmogorov_max_flow(Graph& g,
typename graph_traits<Graph>::vertex_descriptor src,
typename graph_traits<Graph>::vertex_descriptor sink,
const bgl_named_params<P, T, R>& params)
{
return
boykov_kolmogorov_max_flow(
g,
choose_const_pmap(get_param(params, edge_capacity), g, edge_capacity),
choose_pmap(get_param(params, edge_residual_capacity), g, edge_residual_capacity),
choose_const_pmap(get_param(params, edge_reverse), g, edge_reverse),
choose_pmap(get_param(params, vertex_predecessor), g, vertex_predecessor),
choose_pmap(get_param(params, vertex_color), g, vertex_color),
choose_pmap(get_param(params, vertex_distance), g, vertex_distance),
choose_const_pmap(get_param(params, vertex_index), g, vertex_index),
src, sink);
}
/**
* named-parameter version, none given
*/
template<class Graph>
typename property_traits<typename property_map<Graph, edge_capacity_t>::const_type>::value_type
boykov_kolmogorov_max_flow(Graph& g,
typename graph_traits<Graph>::vertex_descriptor src,
typename graph_traits<Graph>::vertex_descriptor sink)
{
bgl_named_params<int, buffer_param_t> params(0); // bogus empty param
return boykov_kolmogorov_max_flow(g, src, sink, params);
}
} // namespace boost
#endif // BOOST_BOYKOV_KOLMOGOROV_MAX_FLOW_HPP