コード例 #1
0
ファイル: flow.cpp プロジェクト: Daron-Wan/snap
/// Returns the amount the flow can be augmented over the paths, 0 if no path can be found. ##TSnap::FindAugV
int FindAugV (const PNEANet &Net, const int& CapIndex, TIntV &Flow, TIntQ &FwdNodeQ, TIntH &PredEdgeH, TIntQ &BwdNodeQ, TIntH &SuccEdgeH, TIntV &MidToSrcAugV, TIntV &MidToSnkAugV, const int& SrcNId, const int& SnkNId) {
  int MidPtNId = IntFlowBiDBFS(Net, CapIndex, Flow, FwdNodeQ, PredEdgeH, BwdNodeQ, SuccEdgeH, SrcNId, SnkNId);
  if (MidPtNId == -1) { return 0; }
  int MinAug = TInt::Mx, NId = MidPtNId, AugFlow = 0;
  // Build the path from the midpoint back to the source by tracing through the PredEdgeH
  for (int EId = PredEdgeH.GetDat(NId); NId != SrcNId; EId = PredEdgeH.GetDat(NId)) {
    MidToSrcAugV.Add(EId);
    const TNEANet::TEdgeI &EI = Net->GetEI(EId);
    if (EI.GetSrcNId() == NId) {
      NId = EI.GetDstNId();
      AugFlow = Flow[EId];
    } else {
      NId = EI.GetSrcNId();
      AugFlow = Net->GetIntAttrIndDatE(EId, CapIndex) - Flow[EId];
    }
    if (AugFlow < MinAug) { MinAug = AugFlow; }
  }
  NId = MidPtNId;
  // Build the path from the midpoint back to the sink by tracing through the SuccEdgeH
  for (int EId = SuccEdgeH.GetDat(NId); NId != SnkNId; EId = SuccEdgeH.GetDat(NId)) {
    MidToSnkAugV.Add(EId);
    const TNEANet::TEdgeI &EI = Net->GetEI(EId);
    if (EI.GetDstNId() == NId) {
      NId = EI.GetSrcNId();
      AugFlow = Flow[EId];
    } else {
      NId = EI.GetDstNId();
      AugFlow = Net->GetIntAttrIndDatE(EId, CapIndex) - Flow[EId];
    }
    if (AugFlow < MinAug) { MinAug = AugFlow; }
  }
  return MinAug;
}
コード例 #2
0
ファイル: flow.cpp プロジェクト: Daron-Wan/snap
int GetMaxFlowIntEK (PNEANet &Net, const int &SrcNId, const int &SnkNId) {
  IAssert(Net->IsNode(SrcNId));
  IAssert(Net->IsNode(SnkNId));
  if (SrcNId == SnkNId) { return 0; }
  int CapIndex = Net->GetIntAttrIndE(CapAttrName);
  TIntV Flow(Net->GetMxEId());
  // Initialize flow values to 0, and make sure capacities are nonnegative
  for (TNEANet::TEdgeI EI = Net->BegEI(); EI != Net->EndEI(); EI++) {
    IAssert(Net->GetIntAttrIndDatE(EI, CapIndex) >= 0);
    Flow[EI.GetId()] = 0;
  }
  // Return 0 if user attempts to flow from a node to itself.
  if (SrcNId == SnkNId) { return 0; }
  int MaxFlow = 0, MinAug, CurNId;
  while (true) {
    TIntV MidToSrcAugV; TIntV MidToSnkAugV;
    TIntQ FwdNodeQ; TIntQ BwdNodeQ;
    TIntH PredEdgeH; TIntH SuccEdgeH;
    MinAug = FindAugV(Net, CapIndex, Flow, FwdNodeQ, PredEdgeH, BwdNodeQ, SuccEdgeH, MidToSrcAugV, MidToSnkAugV, SrcNId, SnkNId);
    if (MinAug == 0) { break; }
    MaxFlow += MinAug;
    CurNId = SrcNId;
    for (int i = MidToSrcAugV.Len() - 1; i >= 0; i--) {
      int NextEId = MidToSrcAugV[i];
      const TNEANet::TEdgeI &EI = Net->GetEI(NextEId);
      if (EI.GetSrcNId() == CurNId) {
        Flow[NextEId] += MinAug;
        CurNId = EI.GetDstNId();
      } else {
        Flow[NextEId] -= MinAug;
        CurNId = EI.GetSrcNId();
      }
    }
    for (int i = 0; i < MidToSnkAugV.Len(); i++) {
      int NextEId = MidToSnkAugV[i];
      const TNEANet::TEdgeI &EI = Net->GetEI(NextEId);
      if (EI.GetSrcNId() == CurNId) {
        Flow[NextEId] += MinAug;
        CurNId = EI.GetDstNId();
      } else {
        Flow[NextEId] -= MinAug;
        CurNId = EI.GetSrcNId();
      }
    }
  }
  return MaxFlow;
}