// computes topological numbering on the segments of the constraint graph.
// Usage: If used on the basic (and vertex size) arcs, the numbering can be
// used in order to serve as sorting criteria for respecting the given
// embedding, e.g., when computing visibility arcs and allowing edges
// with length 0.
void CompactionConstraintGraphBase::computeTopologicalSegmentNum(
NodeArray<int> &topNum)
{
NodeArray<int> indeg(*this);
StackPure<node> sources;
for(node v : nodes) {
topNum[v] = 0;
indeg[v] = v->indeg();
if(indeg[v] == 0)
sources.push(v);
}
while(!sources.empty())
{
node v = sources.pop();
edge e;
forall_adj_edges(e,v) {
if(e->source() != v) continue;
node w = e->target();
if (topNum[w] < topNum[v] + 1)
topNum[w] = topNum[v] + 1;
if (--indeg[w] == 0)
sources.push(w);
}
}
}
int connectedComponents(const Graph &G, NodeArray<int> &component)
{
int nComponent = 0;
component.fill(-1);
StackPure<node> S;
for(node v : G.nodes) {
if (component[v] != -1) continue;
S.push(v);
component[v] = nComponent;
while(!S.empty()) {
node w = S.pop();
edge e;
forall_adj_edges(e,w) {
node x = e->opposite(w);
if (component[x] == -1) {
component[x] = nComponent;
S.push(x);
}
}
}
++nComponent;
}
// extract and add external subgraph from stopnode to ancestors of the node with dfi root
// to edgelist, nodeMarker is used as a visited flag. returns the endnode with lowest dfi.
void FindKuratowskis::extractExternalSubgraphBundles(
const node stop,
int root,
SListPure<edge>& externalSubgraph,
int nodeMarker)
{
node v,temp;
adjEntry adj;
#ifdef OGDF_DEBUG
forall_nodes(v,m_g) OGDF_ASSERT(m_wasHere[v]!=nodeMarker);
#endif
StackPure<node> stack; // stack for dfs-traversal
ListConstIterator<node> it;
stack.push(stop);
while (!stack.empty()) {
v = stack.pop();
if (m_wasHere[v]==nodeMarker) continue;
// mark visited nodes
m_wasHere[v]=nodeMarker;
// search for unvisited nodes and add them to stack
forall_adj(adj,v) {
temp = adj->twinNode();
if (m_edgeType[adj->theEdge()]==EDGE_BACK_DELETED) continue;
// go along backedges to ancestor (ignore virtual nodes)
if (m_dfi[temp] < root && m_dfi[temp] > 0) {
OGDF_ASSERT(m_edgeType[adj->theEdge()]==EDGE_BACK);
externalSubgraph.pushBack(adj->theEdge());
} else if (v != stop && m_dfi[temp]>=m_dfi[v]) {
// set flag and push unvisited nodes
OGDF_ASSERT(m_edgeType[adj->theEdge()]==EDGE_BACK ||
m_edgeType[adj->theEdge()]==EDGE_DFS ||
m_edgeType[adj->theEdge()]==EDGE_BACK_DELETED);
externalSubgraph.pushBack(adj->theEdge());
if (m_wasHere[temp] != nodeMarker) stack.push(temp);
}
}
// descent to external active child bicomps
for (it = m_separatedDFSChildList[v].begin(); it.valid(); ++it) {
temp = *it;
if (m_lowPoint[temp] >= root) break;
stack.push(m_nodeFromDFI[-m_dfi[temp]]);
}
}
void LongestPathCompaction::applyLongestPaths(
const CompactionConstraintGraph<int> &D,
NodeArray<int> &pos)
{
const Graph &Gd = D.getGraph();
m_component.init(Gd);
NodeArray<int> indeg(Gd);
StackPure<node> sources;
for(node v : Gd.nodes) {
indeg[v] = v->indeg();
if(indeg[v] == 0)
sources.push(v);
}
while(!sources.empty())
{
node v = sources.pop();
int predComp = -1; // means "unset"
bool isPseudoSource = true;
edge e;
forall_adj_edges(e,v) {
if(e->source() != v) {
// incoming edge
if (D.cost(e) > 0) {
isPseudoSource = false;
node w = e->source();
// is tight?
if (pos[w] + D.length(e) == pos[v]) {
if (predComp == -1)
predComp = m_component[w];
else if (predComp != m_component[w])
predComp = 0; // means "vertex is in no pseudo-comp.
}
}
} else {
// outgoing edge
node w = e->target();
if (pos[w] < pos[v] + D.length(e))
pos[w] = pos[v] + D.length(e);
if (--indeg[w] == 0)
sources.push(w);
}
}
if (predComp == -1)
predComp = 0;
if( isPseudoSource) {
m_pseudoSources.pushFront(v);
m_component[v] = m_pseudoSources.size();
} else {
m_component[v] = predComp;
}
}
}
// start DFS-traversal
void BoyerMyrvoldInit::computeDFS()
{
// compute random edge costs
EdgeArray<int> costs;
EdgeComparer comp;
if(m_randomness > 0 && m_edgeCosts != nullptr) {
costs.init(m_g);
int minCost = std::numeric_limits<int>::max();
int maxCost = std::numeric_limits<int>::min();
for(edge e : m_g.edges) {
minCost = min(minCost, (*m_edgeCosts)[e]);
maxCost = min(maxCost, (*m_edgeCosts)[e]);
}
std::uniform_real_distribution<> urd(-1, 1);
for(edge e : m_g.edges) {
costs[e] = minCost + (int)((1 - m_randomness) * ((*m_edgeCosts)[e] - minCost) + m_randomness * (maxCost - minCost) * urd(m_rand));
}
comp.setCosts(&costs);
} else if(m_edgeCosts != nullptr) {
comp.setCosts(m_edgeCosts);
}
StackPure<adjEntry> stack;
int nextDFI = 1;
const int numberOfNodes = m_g.numberOfNodes();
SListPure<adjEntry> adjList;
SListPure<node> list;
m_g.allNodes(list);
// get random dfs-tree, if wanted
if (m_randomness > 0) {
list.permute();
}
for (node v : list) {
if (v->degree() == 0) {
m_dfi[v] = nextDFI;
m_leastAncestor[v] = nextDFI;
m_nodeFromDFI[nextDFI] = v;
++nextDFI;
} else {
adjList.clear();
m_g.adjEntries(v, adjList);
adjList.quicksort(comp);
m_g.sort(v, adjList);
stack.push(v->firstAdj());
}
}
while (nextDFI <= numberOfNodes) {
OGDF_ASSERT(!stack.empty());
adjEntry prnt = stack.pop();
node v = prnt->theNode();
// check, if node v was visited before.
if (m_dfi[v] != 0) continue;
// parentNode=nullptr on first node on connected component
node parentNode = prnt->twinNode();
if (m_dfi[parentNode] == 0) parentNode = nullptr;
// if not, mark node as visited and initialize NodeArrays
m_dfi[v] = nextDFI;
m_leastAncestor[v] = nextDFI;
m_nodeFromDFI[nextDFI] = v;
++nextDFI;
// push all adjacent nodes onto stack
for(adjEntry adj : v->adjEdges) {
edge e = adj->theEdge();
if (adj == prnt && parentNode != nullptr) continue;
// check for self-loops and dfs- and dfs-parallel edges
node w = adj->twinNode();
if (m_dfi[w] == 0) {
m_edgeType[e] = EDGE_DFS;
m_adjParent[w] = adj;
m_link[CW][w] = adj;
m_link[CCW][w] = adj;
// found new dfs-edge: preorder
stack.push(adj->twin());
} else if (w == v) {
// found self-loop
m_edgeType[e] = EDGE_SELFLOOP;
} else {
// node w already has been visited and is an dfs-ancestor of v
OGDF_ASSERT(m_dfi[w] < m_dfi[v]);
if (w == parentNode) {
// found parallel edge of dfs-parent-edge
m_edgeType[e] = EDGE_DFS_PARALLEL;
} else {
// found backedge
m_edgeType[e] = EDGE_BACK;
// set least Ancestor
if (m_dfi[w] < m_leastAncestor[v])
m_leastAncestor[v] = m_dfi[w];
}
}
}
}
}
