/// Returns the ID of the neighbor that \c NId pushes to, -1 if no push was made.
int PushRelabel (TPRManager &PRM, const int &NId, const TNEANet::TNodeI &NI) {
int EdgeN = PRM.EdgeNum(NId);
int EId = -1, NbrNId = -1, ResFlow = 0;
int Cutoff = NI.GetInDeg();
if (EdgeN < Cutoff) {
EId = NI.GetInEId(EdgeN);
NbrNId = NI.GetInNId(EdgeN);
ResFlow = PRM.Flow(EId);
} else {
EId = NI.GetOutEId(EdgeN - Cutoff);
NbrNId = NI.GetOutNId(EdgeN - Cutoff);
ResFlow = PRM.Capacity(EId) - PRM.Flow(EId);
}
if (ResFlow > 0 && PRM.Label(NId) - 1 == PRM.Label(NbrNId)) {
if (EdgeN < Cutoff) {
PushToInNbr(PRM, NId, NbrNId, EId);
} else {
PushToOutNbr(PRM, NId, NbrNId, EId);
}
return NbrNId;
}
if (EdgeN + 1 == NI.GetDeg()) {
PRM.EdgeNum(NId) = 0;
Relabel(PRM, NId, NI);
} else {
PRM.EdgeNum(NId)++;
}
return -1;
}
/// Increases the label of a node \c NId to allow valid pushes to some neighbor.
void Relabel (TPRManager &PRM, const int &NId, const TNEANet::TNodeI &NI) {
int MaxLabel = PRM.GetMaxLabel();
int MinLabel = MaxLabel;
for (int EdgeN = 0; EdgeN < NI.GetInDeg(); EdgeN++) {
if (PRM.Flow(NI.GetInEId(EdgeN)) > 0) {
int InLabel = PRM.Label(NI.GetInNId(EdgeN));
MinLabel = min(MinLabel, InLabel);
}
}
for (int EdgeN = 0; EdgeN < NI.GetOutDeg(); EdgeN++) {
if (PRM.Capacity(NI.GetOutEId(EdgeN)) > PRM.Flow(NI.GetOutEId(EdgeN))) {
int OutLabel = PRM.Label(NI.GetOutNId(EdgeN));
MinLabel = min(MinLabel, OutLabel);
}
}
if (MinLabel == MaxLabel) {
PRM.SetLabel(NId, MaxLabel);
} else {
PRM.SetLabel(NId, MinLabel + 1);
}
}
int GetMaxFlowIntPR (PNEANet &Net, const int& SrcNId, const int& SnkNId) {
IAssert(Net->IsNode(SrcNId));
IAssert(Net->IsNode(SnkNId));
if (SrcNId == SnkNId) { return 0; }
TPRManager PRM(Net);
int MaxLabel = PRM.GetMaxLabel();
TNEANet::TNodeI SrcNI = Net->GetNI(SrcNId);
for (int EdgeN = 0; EdgeN < SrcNI.GetOutDeg(); EdgeN++) {
int EId = SrcNI.GetOutEId(EdgeN);
int OutNId = SrcNI.GetOutNId(EdgeN);
if (OutNId != SrcNId) {
int Capacity = PRM.Capacity(EId);
PRM.Flow(EId) = Capacity;
PRM.Excess(OutNId) = Capacity;
}
}
GlobalRelabel(Net, PRM, SrcNId, SnkNId);
PRM.SetLabel(SrcNId, MaxLabel);
int RelabelCount = 1;
int GRRate = Net->GetNodes();
while (PRM.HasActive()) {
int NId = PRM.PopActive();
const TNEANet::TNodeI &NI = Net->GetNI(NId);
int PrevLabel = MaxLabel;
while (PRM.Excess(NId) > 0 && PRM.Label(NId) <= PrevLabel) {
PrevLabel = PRM.Label(NId);
int NbrNId = PushRelabel(PRM, NId, NI);
if (NbrNId != -1 && NbrNId != SnkNId && PRM.Excess(NbrNId) > 0 && !PRM.IsActive(NbrNId)) {
PRM.PushActive(NbrNId);
}
}
if (PRM.Excess(NId) > 0 && PRM.Label(NId) < MaxLabel) {
PRM.PushActive(NId);
}
if (RelabelCount % GRRate == 0) { GlobalRelabel(Net, PRM, SrcNId, SnkNId); }
}
return PRM.Excess(SnkNId);
}
