SNAP should support finding the NId(s) with the minimum degree

[smemery]

SNAP should support finding the NId(s) with the minimum degree. The following is the delta to add support:

--- snap-core/alg.h.old 2023-12-09 22:16:39.458539066 -0700
+++ snap-core/alg.h 2023-12-09 22:32:35.778365319 -0700
@@ -19,10 +19,17 @@
/// Returns a randomly chosen node from all the nodes with the maximum in-degree.
template int GetMxInDegNId(const PGraph& Graph);
/// Returns a randomly chosen node from all the nodes with the maximum out-degree.
template int GetMxOutDegNId(const PGraph& Graph);

+/// Returns a randomly chosen node from all the nodes with the minimum degree.
+template int GetMnDegNId(const PGraph& Graph);
+/// Returns a randomly chosen node from all the nodes with the minimum in-degree.
+template int GetMnInDegNId(const PGraph& Graph);
+/// Returns a randomly chosen node from all the nodes with the minimum out-degree.
+template int GetMnOutDegNId(const PGraph& Graph);
+
// degree histograms
/// Returns an in-degree histogram: a set of pairs (in-degree, number of nodes of such in-degree)
template void GetInDegCnt(const PGraph& Graph, TIntPrV& DegToCntV);
/// Returns an in-degree histogram: a set of pairs (in-degree, number of nodes of such in-degree)
template void GetInDegCnt(const PGraph& Graph, TFltPrV& DegToCntV);
@@ -174,10 +181,46 @@
EAssertR(! MxDegV.Empty(), "Input graph is empty!");
return MxDegV[TInt::Rnd.GetUniDevInt(MxDegV.Len())];
}

template
+int GetMnDegNId(const PGraph& Graph) {

• TIntV MnDegV;
• int MnDeg=INT_MAX;
• for (typename PGraph::TObj::TNodeI NI = Graph->BegNI(); NI < Graph->EndNI(); NI++) {
• if (MnDeg > NI.GetDeg()) { MnDegV.Clr(); MnDeg = NI.GetDeg(); }
• if (MnDeg == NI.GetDeg()) { MnDegV.Add(NI.GetId()); }
• }
• EAssertR(! MnDegV.Empty(), "Input graph is empty!");
• return MnDegV[TInt::Rnd.GetUniDevInt(MnDegV.Len())];
  +}

+template
+int GetMnInDegNId(const PGraph& Graph) {

• TIntV MnDegV;
• int MnDeg=INT_MAX;
• for (typename PGraph::TObj::TNodeI NI = Graph->BegNI(); NI < Graph->EndNI(); NI++) {
• if (MnDeg > NI.GetInDeg()) { MnDegV.Clr(); MnDeg = NI.GetInDeg(); }
• if (MnDeg == NI.GetInDeg()) { MnDegV.Add(NI.GetId()); }
• }
• EAssertR(! MnDegV.Empty(), "Input graph is empty!");
• return MnDegV[TInt::Rnd.GetUniDevInt(MnDegV.Len())];
  +}

+template
+int GetMnOutDegNId(const PGraph& Graph) {

• TIntV MnDegV;
• int MnDeg=INT_MAX;
• for (typename PGraph::TObj::TNodeI NI = Graph->BegNI(); NI < Graph->EndNI(); NI++) {
• if (MnDeg > NI.GetOutDeg()) { MnDegV.Clr(); MnDeg = NI.GetOutDeg(); }
• if (MnDeg == NI.GetOutDeg()) { MnDegV.Add(NI.GetId()); }
• }
• EAssertR(! MnDegV.Empty(), "Input graph is empty!");
• return MnDegV[TInt::Rnd.GetUniDevInt(MnDegV.Len())];
  +}

+template
void GetInDegCnt(const PGraph& Graph, TIntPrV& DegToCntV) {
TIntH DegToCntH;
for (typename PGraph::TObj::TNodeI NI = Graph->BegNI(); NI < Graph->EndNI(); NI++) {
DegToCntH.AddDat(NI.GetInDeg())++; }
DegToCntV.Gen(DegToCntH.Len(), 0);