int FixedOrCommonCandidates(Node * N)
{
int Count = 0;
Count = N->FixedTo2 ? 2 : N->FixedTo1 ? 1 : 0;
if (MergeTourFiles >= 2) {
if (!Fixed(N, N->MergeSuc[0]) && IsCommonEdge(N, N->MergeSuc[0]))
Count++;
if (!Fixed(N->MergePred, N) && IsCommonEdge(N->MergePred, N))
Count++;
}
if (Count > 2)
eprintf("Node %d has more than two required candidate edges",
N->Id);
return Count;
}
void ChooseInitialTour()
{
Node *N, *NextN, *FirstAlternative, *Last;
Candidate *NN;
int Alternatives, Count, i;
if (KickType > 0 && Kicks > 0 && Trial > 1) {
for (Last = FirstNode; (N = Last->BestSuc) != FirstNode; Last = N)
Follow(N, Last);
for (i = 1; i <= Kicks; i++)
KSwapKick(KickType);
return;
}
if (Trial == 1 && (!FirstNode->InitialSuc || InitialTourFraction < 1)) {
if (InitialTourAlgorithm == BORUVKA ||
InitialTourAlgorithm == GREEDY ||
InitialTourAlgorithm == MOORE ||
InitialTourAlgorithm == NEAREST_NEIGHBOR ||
InitialTourAlgorithm == QUICK_BORUVKA ||
InitialTourAlgorithm == SIERPINSKI) {
GainType Cost = InitialTourAlgorithm == MOORE ||
InitialTourAlgorithm == SIERPINSKI ?
SFCTour(InitialTourAlgorithm) : GreedyTour();
if (MaxTrials == 0) {
BetterCost = Cost;
RecordBetterTour();
}
if (!FirstNode->InitialSuc)
return;
}
}
Start:
/* Mark all nodes as "not chosen" by setting their V field to zero */
N = FirstNode;
do
N->V = 0;
while ((N = N->Suc) != FirstNode);
Count = 0;
/* Choose FirstNode without two incident fixed or common candidate edges */
do {
if (FixedOrCommonCandidates(N) < 2)
break;
}
while ((N = N->Suc) != FirstNode);
if (ProblemType == ATSP && N->Id <= DimensionSaved)
N += DimensionSaved;
FirstNode = N;
/* Move nodes with two incident fixed or common candidate edges in
front of FirstNode */
for (Last = FirstNode->Pred; N != Last; N = NextN) {
NextN = N->Suc;
if (FixedOrCommonCandidates(N) == 2)
Follow(N, Last);
}
/* Mark FirstNode as chosen */
FirstNode->V = 1;
N = FirstNode;
/* Loop as long as not all nodes have been chosen */
while (N->Suc != FirstNode) {
FirstAlternative = 0;
Alternatives = 0;
Count++;
/* Case A */
for (NN = N->CandidateSet; (NextN = NN->To); NN++) {
if (!NextN->V && Fixed(N, NextN)) {
Alternatives++;
NextN->Next = FirstAlternative;
FirstAlternative = NextN;
}
}
if (Alternatives == 0 && MergeTourFiles > 1) {
for (NN = N->CandidateSet; (NextN = NN->To); NN++) {
if (!NextN->V && IsCommonEdge(N, NextN)) {
Alternatives++;
NextN->Next = FirstAlternative;
FirstAlternative = NextN;
}
}
}
if (Alternatives == 0 && FirstNode->InitialSuc && Trial == 1 &&
Count <= InitialTourFraction * Dimension) {
/* Case B */
for (NN = N->CandidateSet; (NextN = NN->To); NN++) {
if (!NextN->V && InInitialTour(N, NextN)) {
Alternatives++;
NextN->Next = FirstAlternative;
FirstAlternative = NextN;
}
}
}
if (Alternatives == 0 && Trial > 1 &&
ProblemType != HCP && ProblemType != HPP) {
/* Case C */
for (NN = N->CandidateSet; (NextN = NN->To); NN++) {
if (!NextN->V && FixedOrCommonCandidates(NextN) < 2 &&
NN->Alpha == 0 && (InBestTour(N, NextN) ||
InNextBestTour(N, NextN))) {
Alternatives++;
NextN->Next = FirstAlternative;
FirstAlternative = NextN;
}
}
}
if (Alternatives == 0) {
/* Case D */
for (NN = N->CandidateSet; (NextN = NN->To); NN++) {
if (!NextN->V && FixedOrCommonCandidates(NextN) < 2) {
Alternatives++;
NextN->Next = FirstAlternative;
FirstAlternative = NextN;
}
}
}
if (Alternatives == 0) {
/* Case E (actually not really a random choice) */
NextN = N->Suc;
while ((FixedOrCommonCandidates(NextN) == 2 || Forbidden(N, NextN))
&& NextN->Suc != FirstNode)
NextN = NextN->Suc;
if (FixedOrCommonCandidates(NextN) == 2 || Forbidden(N, NextN)) {
FirstNode = FirstNode->Suc;
goto Start;
}
} else {
NextN = FirstAlternative;
if (Alternatives > 1) {
/* Select NextN at random among the alternatives */
i = Random() % Alternatives;
while (i--)
NextN = NextN->Next;
}
}
/* Include NextN as the successor of N */
Follow(NextN, N);
N = NextN;
N->V = 1;
}
if (Forbidden(N, N->Suc)) {
FirstNode = FirstNode->Suc;
goto Start;
}
if (MaxTrials == 0) {
GainType Cost = 0;
N = FirstNode;
do
Cost += C(N, N->Suc) - N->Pi - N->Suc->Pi;
while ((N = N->Suc) != FirstNode);
Cost /= Precision;
if (Cost < BetterCost) {
BetterCost = Cost;
RecordBetterTour();
}
}
}
