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#ifndef _CV_GCGRAPH_H_
#define _CV_GCGRAPH_H_
template <class TWeight> class GCGraph
{
public:
GCGraph();
GCGraph( unsigned int vtxCount, unsigned int edgeCount );
~GCGraph();
void create( unsigned int vtxCount, unsigned int edgeCount );
int addVtx();
void addEdges( int i, int j, TWeight w, TWeight revw );
void addTermWeights( int i, TWeight sourceW, TWeight sinkW );
TWeight maxFlow();
bool inSourceSegment( int i );
private:
class Vtx
{
public:
Vtx *next; // initialized and used in maxFlow() only
int parent;
int first;
int ts;
int dist;
TWeight weight;
uchar t;
};
class Edge
{
public:
int dst;
int next;
TWeight weight;
};
std::vector<Vtx> vtcs;
std::vector<Edge> edges;
TWeight flow;
};
template <class TWeight>
GCGraph<TWeight>::GCGraph()
{
flow = 0;
}
template <class TWeight>
GCGraph<TWeight>::GCGraph( unsigned int vtxCount, unsigned int edgeCount )
{
create( vtxCount, edgeCount );
}
template <class TWeight>
GCGraph<TWeight>::~GCGraph()
{
}
template <class TWeight>
void GCGraph<TWeight>::create( unsigned int vtxCount, unsigned int edgeCount )
{
vtcs.reserve( vtxCount );
edges.reserve( edgeCount + 2 );
flow = 0;
}
template <class TWeight>
int GCGraph<TWeight>::addVtx()
{
Vtx v;
memset( &v, 0, sizeof(Vtx));
vtcs.push_back(v);
return (int)vtcs.size() - 1;
}
template <class TWeight>
void GCGraph<TWeight>::addEdges( int i, int j, TWeight w, TWeight revw )
{
CV_Assert( i>=0 && i<(int)vtcs.size() );
CV_Assert( j>=0 && j<(int)vtcs.size() );
CV_Assert( w>=0 && revw>=0 );
CV_Assert( i != j );
if( !edges.size() )
edges.resize( 2 );
Edge fromI, toI;
fromI.dst = j;
fromI.next = vtcs[i].first;
fromI.weight = w;
vtcs[i].first = (int)edges.size();
edges.push_back( fromI );
toI.dst = i;
toI.next = vtcs[j].first;
toI.weight = revw;
vtcs[j].first = (int)edges.size();
edges.push_back( toI );
}
template <class TWeight>
void GCGraph<TWeight>::addTermWeights( int i, TWeight sourceW, TWeight sinkW )
{
CV_Assert( i>=0 && i<(int)vtcs.size() );
TWeight dw = vtcs[i].weight;
if( dw > 0 )
sourceW += dw;
else
sinkW -= dw;
flow += (sourceW < sinkW) ? sourceW : sinkW;
vtcs[i].weight = sourceW - sinkW;
}
template <class TWeight>
TWeight GCGraph<TWeight>::maxFlow()
{
const int TERMINAL = -1, ORPHAN = -2;
Vtx stub, *nilNode = &stub, *first = nilNode, *last = nilNode;
int curr_ts = 0;
stub.next = nilNode;
Vtx *vtxPtr = &vtcs[0];
Edge *edgePtr = &edges[0];
std::vector<Vtx*> orphans;
// initialize the active queue and the graph vertices
for( int i = 0; i < (int)vtcs.size(); i++ )
{
Vtx* v = vtxPtr + i;
v->ts = 0;
if( v->weight != 0 )
{
last = last->next = v;
v->dist = 1;
v->parent = TERMINAL;
v->t = v->weight < 0;
}
else
v->parent = 0;
}
first = first->next;
last->next = nilNode;
nilNode->next = 0;
// run the search-path -> augment-graph -> restore-trees loop
for(;;)
{
Vtx* v, *u;
int e0 = -1, ei = 0, ej = 0;
TWeight minWeight, weight;
uchar vt;
// grow S & T search trees, find an edge connecting them
while( first != nilNode )
{
v = first;
if( v->parent )
{
vt = v->t;
for( ei = v->first; ei != 0; ei = edgePtr[ei].next )
{
if( edgePtr[ei^vt].weight == 0 )
continue;
u = vtxPtr+edgePtr[ei].dst;
if( !u->parent )
{
u->t = vt;
u->parent = ei ^ 1;
u->ts = v->ts;
u->dist = v->dist + 1;
if( !u->next )
{
u->next = nilNode;
last = last->next = u;
}
continue;
}
if( u->t != vt )
{
e0 = ei ^ vt;
break;
}
if( u->dist > v->dist+1 && u->ts <= v->ts )
{
// reassign the parent
u->parent = ei ^ 1;
u->ts = v->ts;
u->dist = v->dist + 1;
}
}
if( e0 > 0 )
break;
}
// exclude the vertex from the active list
first = first->next;
v->next = 0;
}
if( e0 <= 0 )
break;
// find the minimum edge weight along the path
minWeight = edgePtr[e0].weight;
CV_Assert( minWeight > 0 );
// k = 1: source tree, k = 0: destination tree
for( int k = 1; k >= 0; k-- )
{
for( v = vtxPtr+edgePtr[e0^k].dst;; v = vtxPtr+edgePtr[ei].dst )
{
if( (ei = v->parent) < 0 )
break;
weight = edgePtr[ei^k].weight;
minWeight = MIN(minWeight, weight);
CV_Assert( minWeight > 0 );
}
weight = fabs(v->weight);
minWeight = MIN(minWeight, weight);
CV_Assert( minWeight > 0 );
}
// modify weights of the edges along the path and collect orphans
edgePtr[e0].weight -= minWeight;
edgePtr[e0^1].weight += minWeight;
flow += minWeight;
// k = 1: source tree, k = 0: destination tree
for( int k = 1; k >= 0; k-- )
{
for( v = vtxPtr+edgePtr[e0^k].dst;; v = vtxPtr+edgePtr[ei].dst )
{
if( (ei = v->parent) < 0 )
break;
edgePtr[ei^(k^1)].weight += minWeight;
if( (edgePtr[ei^k].weight -= minWeight) == 0 )
{
orphans.push_back(v);
v->parent = ORPHAN;
}
}
v->weight = v->weight + minWeight*(1-k*2);
if( v->weight == 0 )
{
orphans.push_back(v);
v->parent = ORPHAN;
}
}
// restore the search trees by finding new parents for the orphans
curr_ts++;
while( !orphans.empty() )
{
Vtx* v2 = orphans.back();
orphans.pop_back();
int d, minDist = INT_MAX;
e0 = 0;
vt = v2->t;
for( ei = v2->first; ei != 0; ei = edgePtr[ei].next )
{
if( edgePtr[ei^(vt^1)].weight == 0 )
continue;
u = vtxPtr+edgePtr[ei].dst;
if( u->t != vt || u->parent == 0 )
continue;
// compute the distance to the tree root
for( d = 0;; )
{
if( u->ts == curr_ts )
{
d += u->dist;
break;
}
ej = u->parent;
d++;
if( ej < 0 )
{
if( ej == ORPHAN )
d = INT_MAX-1;
else
{
u->ts = curr_ts;
u->dist = 1;
}
break;
}
u = vtxPtr+edgePtr[ej].dst;
}
// update the distance
if( ++d < INT_MAX )
{
if( d < minDist )
{
minDist = d;
e0 = ei;
}
for( u = vtxPtr+edgePtr[ei].dst; u->ts != curr_ts; u = vtxPtr+edgePtr[u->parent].dst )
{
u->ts = curr_ts;
u->dist = --d;
}
}
}
if( (v2->parent = e0) > 0 )
{
v2->ts = curr_ts;
v2->dist = minDist;
continue;
}
/* no parent is found */
v2->ts = 0;
for( ei = v2->first; ei != 0; ei = edgePtr[ei].next )
{
u = vtxPtr+edgePtr[ei].dst;
ej = u->parent;
if( u->t != vt || !ej )
continue;
if( edgePtr[ei^(vt^1)].weight && !u->next )
{
u->next = nilNode;
last = last->next = u;
}
if( ej > 0 && vtxPtr+edgePtr[ej].dst == v2 )
{
orphans.push_back(u);
u->parent = ORPHAN;
}
}
}
}
return flow;
}
template <class TWeight>
bool GCGraph<TWeight>::inSourceSegment( int i )
{
CV_Assert( i>=0 && i<(int)vtcs.size() );
return vtcs[i].t == 0;
}
#endif