int AddCandidate(Node * From, Node * To, int Cost, int Alpha)
{
int Count;
Candidate *NFrom;
if (From->Subproblem != FirstNode->Subproblem)
return 0;
if (From->CandidateSet == 0)
assert(From->CandidateSet =
(Candidate *) calloc(3, sizeof(Candidate)));
if (From == To || To->Subproblem != FirstNode->Subproblem ||
!IsPossibleCandidate(From, To))
return 0;
Count = 0;
for (NFrom = From->CandidateSet; NFrom->To && NFrom->To != To; NFrom++)
Count++;
if (NFrom->To) {
if (NFrom->Alpha == INT_MAX)
NFrom->Alpha = Alpha;
return 0;
}
NFrom->Cost = Cost;
NFrom->Alpha = Alpha;
NFrom->To = To;
assert(From->CandidateSet =
(Candidate *) realloc(From->CandidateSet,
(Count + 2) * sizeof(Candidate)));
From->CandidateSet[Count + 1].To = 0;
return 1;
}
void LKH::LKHAlg::GenerateCandidates(int MaxCandidates, GainType MaxAlpha,
int Symmetric)
{
Node *From, *To;
Candidate *NFrom, *NN;
int a, d, Count;
if (TraceLevel >= 2)
printff("Generating candidates ... ");
if (MaxAlpha < 0 || MaxAlpha > INT_MAX)
MaxAlpha = INT_MAX;
/* Initialize CandidateSet for each node */
FreeCandidateSets();
From = FirstNode;
do
From->Mark = 0;
while ((From = From->Suc) != FirstNode);
if (MaxCandidates > 0) {
do {
assert(From->CandidateSet =
(Candidate *) malloc((MaxCandidates + 1) *
sizeof(Candidate)));
From->CandidateSet[0].To = 0;
}
while ((From = From->Suc) != FirstNode);
} else {
AddTourCandidates();
do {
if (!From->CandidateSet)
eprintf("MAX_CANDIDATES = 0: No candidates");
} while ((From = From->Suc) != FirstNode);
return;
}
/* Loop for each node, From */
do {
NFrom = From->CandidateSet;
if (From != FirstNode) {
From->Beta = INT_MIN;
for (To = From; To->Dad != 0; To = To->Dad) {
To->Dad->Beta =
!FixedOrCommon(To, To->Dad) ?
Max(To->Beta, To->Cost) : To->Beta;
To->Dad->Mark = From;
}
}
Count = 0;
/* Loop for each node, To */
To = FirstNode;
do {
if (To == From)
continue;
d = c && !FixedOrCommon(From, To) ? (this->*c)(From, To) : (this->*D)(From, To);
if (From == FirstNode)
a = To == From->Dad ? 0 : d - From->NextCost;
else if (To == FirstNode)
a = From == To->Dad ? 0 : d - To->NextCost;
else {
if (To->Mark != From)
To->Beta =
!FixedOrCommon(To, To->Dad) ?
Max(To->Dad->Beta, To->Cost) : To->Dad->Beta;
a = d - To->Beta;
}
if (FixedOrCommon(From, To))
a = INT_MIN;
else {
if (From->FixedTo2 || To->FixedTo2 || Forbidden(From, To))
continue;
if (InInputTour(From, To)) {
a = 0;
if (c)
d = (this->*D)(From, To);
} else if (c) {
if (a > MaxAlpha ||
(Count == MaxCandidates &&
(a > (NFrom - 1)->Alpha ||
(a == (NFrom - 1)->Alpha
&& d >= (NFrom - 1)->Cost))))
continue;
if (To == From->Dad) {
d = From->Cost;
a = 0;
} else if (From == To->Dad) {
d = To->Cost;
a = 0;
} else {
a -= d;
a += (d = (this->*D)(From, To));
}
}
}
if (a <= MaxAlpha && IsPossibleCandidate(From, To)) {
/* Insert new candidate edge in From->CandidateSet */
NN = NFrom;
while (--NN >= From->CandidateSet) {
if (a > NN->Alpha || (a == NN->Alpha && d >= NN->Cost))
break;
*(NN + 1) = *NN;
}
NN++;
NN->To = To;
NN->Cost = d;
NN->Alpha = a;
if (Count < MaxCandidates) {
Count++;
NFrom++;
}
NFrom->To = 0;
}
}
while ((To = To->Suc) != FirstNode);
}
while ((From = From->Suc) != FirstNode);
AddTourCandidates();
if (Symmetric)
SymmetrizeCandidateSet();
if (TraceLevel >= 2)
printff("done\n");
}
