void LazyConstraintCallback::processGraph( int index ) {
Graph const & graph = graphs.graph( index );
GraphVariables const & vars = graphs.variables( index );
IloNumArray x_values{ getEnv(), vars.xVars.getSize() };
getValues( x_values, vars.xVars );
IloNumArray y_values{ getEnv(), vars.yVars.getSize() };
getValues( y_values, vars.yVars );
//printNonZeroX( x_values, index );
//printNonZeroY( y_values, index );
int nCuts = 0;
NodeSetVector nonZeroNodesComponents;
constructNonZeroComponents( graph, vars, x_values, nonZeroNodesComponents );
if ( nonZeroNodesComponents.size() > 1 ) {
Graph::Node root = determineRoot( graph, vars, y_values );
separateConnectedComponents( graph
, vars
, root
, nonZeroNodesComponents
, nCuts
);
}
x_values.end();
y_values.end();
//clog << "Generated " << nCuts << " cuts" << endl;
}
void Callback::constructNonZeroComponents( Graph const & g
, GraphVariables const & vars
, IloNumArray x_values
, NodeSetVector & nonZeroNodesComponents
) const {
using NodeQueue = std::queue< Graph::Node >;
NodeQueue queue;
// -3 queued
// -2 unvisited
// -1 visited and zero
// >= 0 visited and non-zero
auto compMap = g.createNodeMap< int >( -2 );
int compIdx = 0;
for ( Graph::Node n : g.nodes() ) {
if ( compMap[n] == -2 && intIsNonZero( x_values[vars.nodeToIndex[n]] ) ) {
queue.push( n );
compMap[n] = -3;
nonZeroNodesComponents.emplace_back();
// perform bfs
while ( !queue.empty() ) {
Graph::Node n = queue.front();
assert( compMap[n] == -3 );
queue.pop();
compMap[n] = compIdx;
nonZeroNodesComponents.back().insert( n );
for ( Graph::Edge e : g.incEdges( n ) ) {
Graph::Node nn = g.oppositeNode( n, e );
if ( compMap[nn] == -2 ) {
if ( intIsNonZero( x_values[vars.nodeToIndex[nn]] ) ) {
queue.push( nn );
compMap[nn] = -3;
} else {
compMap[nn] = -1;
}
}
}
}
++compIdx;
}
}
}
int TarjanHD::constructCondensedGraph(const Digraph& g,
const DoubleArcMap& w,
const NodeNodeMap& mapToOrgG,
const NodeNodeMap& G2T,
const ArcList& sortedArcs,
const IntNodeMap& comp,
const NodeSetVector& components,
const NodeVector& roots,
const int j,
Digraph& c,
DoubleArcMap& ww,
NodeNodeMap& mapCToOrgG,
NodeNodeMap& C2T,
ArcList& newSortedArcs)
{
// construct the condensed graph:
// each strongly connected component is collapsed into a single node, and
// from the resulting sets of multiple arcs retain only those with minimum weight
lemon::DynArcLookUp<Digraph> lookUpArc(c);
// first construct the nodes
const size_t numSCC = components.size();
NodeVector nodesOfC(numSCC, lemon::INVALID);
for (size_t k = 0; k < numSCC; ++k)
{
Node v = nodesOfC[k] = c.addNode();
if (components[k].size() == 1)
{
mapCToOrgG[v] = mapToOrgG[*components[k].begin()];
C2T[v] = G2T[*components[k].begin()];
}
else
{
mapCToOrgG[v] = lemon::INVALID;
C2T[v] = roots[k];
}
}
// next construct the arcs: O(m) time
for (ArcListIt arcIt = sortedArcs.begin(); arcIt != sortedArcs.end(); ++arcIt)
{
Arc a = *arcIt;
Node u = g.source(a);
Node v = g.target(a);
Node uu = nodesOfC[comp[u]];
Node vv = nodesOfC[comp[v]];
if (uu != vv)
{
Arc aa = lookUpArc(uu, vv);
if (aa == lemon::INVALID)
{
aa = c.addArc(uu, vv);
newSortedArcs.push_back(aa);
ww[aa] = w[a];
}
#ifdef DEBUG
else
{
assert(w[a] > ww[aa]);
}
#endif
}
}
return get_i(newSortedArcs, ww, w[getArcByRank(sortedArcs, j)]);
}
