// Remove the top node from the heap
void
CbcTree::pop()
{
# if CBC_DEBUG_HEAP > 2
CbcNode *node = nodes_.front() ;
CbcNodeInfo *info = node->nodeInfo() ;
assert(info) ;
std::cout
<< " HEAP: Popping node " << node->nodeNumber()
<< "(" << std::hex << node << std::dec
<< ") obj " << node->objectiveValue()
<< ", ref " << info->decrement(0)
<< ", todo " << info->numberBranchesLeft()
<< ", refd by " << info->numberPointingToThis() << "." << std::endl ;
# endif
# if CBC_DEBUG_HEAP > 0
validateHeap() ;
# endif
nodes_.front()->setOnTree(false);
std::pop_heap(nodes_.begin(), nodes_.end(), comparison_);
nodes_.pop_back();
# if CBC_DEBUG_HEAP > 0
validateHeap() ;
# endif
}
// Start dive
void
CbcCompareDefault::startDive(CbcModel * model)
{
// Get best - using ? criterion
double saveWeight = weight_;
weight_ = 0.5 * saveWeight_; //0.0;
// Switch off to get best
startNodeNumber_ = -1;
afterNodeNumber_ = -1;
CbcNode * best = model->tree()->bestAlternate();
startNodeNumber_ = best->nodeNumber();
// send signal to setComparison
setupForDiving_ = true ;
/*
TODO (review when fixing cleanDive and setComparison)
Both afterNodeNumber_ and weight_ must not change
after setComparison is invoked, as that will change
the behaviour of test(). I replaced the overload on
afterNodeNumber_ (magic number -2) with a boolean. Weight_
is more problematic. Either it's correct before calling
setComparison, or it needs to be cut from the tie-breaking
part of test() during a dive, or there needs to be a new
attribute to save and restore it around the dive. Otherwise
heap checks fail in debug builds with Visual Studio.
Given that weight_ was restored immediately after the call
to setComparison, there should be no change in behaviour
in terms of calls to test().
-- lh, 100921 --
*/
afterNodeNumber_ = model->tree()->maximumNodeNumber();
weight_ = saveWeight ;
// redo tree
model->tree()->setComparison(*this);
setupForDiving_ = false ;
}
// Gets best node and takes off heap
CbcNode *
CbcTreeArray::bestNode(double cutoff)
{
CbcNode * best = NULL;
// See if we want last node or best on heap
if (lastNode_) {
#ifdef CBCTREE_PRINT
printf("Best lastNode_ %x (%x at depth %d) - nodeNumber %d obj %g\n",
lastNode_, lastNode_->nodeInfo(), lastNode_->depth(),
lastNode_->nodeNumber(), lastNode_->objectiveValue());
#endif
assert (lastNode_->onTree());
int nodeNumber = lastNode_->nodeNumber();
bool useLastNode = false;
if (nodeNumber + 1 == maximumNodeNumber_) {
// diving - look further
CbcCompareDefault * compareDefault
= dynamic_cast<CbcCompareDefault *> (comparison_.test_);
assert (compareDefault);
double bestPossible = compareDefault->getBestPossible();
double cutoff = compareDefault->getCutoff();
double objValue = lastNode_->objectiveValue();
if (cutoff < 1.0e20) {
if (objValue - bestPossible < 0.999*(cutoff - bestPossible))
useLastNode = true;
} else {
useLastNode = true;
}
}
if (useLastNode) {
lastNode_->setOnTree(false);
best = lastNode_;
lastNode_ = NULL;
assert(best->objectiveValue() != COIN_DBL_MAX && best->nodeInfo());
if (best->objectiveValue() != COIN_DBL_MAX && best->nodeInfo())
assert (best->nodeInfo()->numberBranchesLeft());
if (best->objectiveValue() >= cutoff) {
// double check in case node can change its mind!
best->checkIsCutoff(cutoff);
}
lastNodePopped_ = best;
return best;
} else {
// put on tree
nodes_.push_back(lastNode_);
lastNode_->setNodeNumber(maximumNodeNumber_);
maximumNodeNumber_++;
lastNode_ = NULL;
std::push_heap(nodes_.begin(), nodes_.end(), comparison_);
}
}
while (!best && nodes_.size()) {
best = nodes_.front();
if (best)
assert(best->objectiveValue() != COIN_DBL_MAX && best->nodeInfo());
if (best && best->objectiveValue() != COIN_DBL_MAX && best->nodeInfo())
assert (best->nodeInfo()->numberBranchesLeft());
if (best && best->objectiveValue() >= cutoff) {
// double check in case node can change its mind!
best->checkIsCutoff(cutoff);
}
if (!best || best->objectiveValue() >= cutoff) {
// let code get rid of it
assert (best);
}
}
lastNodePopped_ = best;
#ifdef CBCTREE_PRINT
if (best)
printf("Heap returning node %x (%x at depth %d) - nodeNumber %d - obj %g\n",
best, best->nodeInfo(), best->depth(),
best->nodeNumber(), best->objectiveValue());
else
printf("Heap returning Null\n");
#endif
if (best) {
// take off
std::pop_heap(nodes_.begin(), nodes_.end(), comparison_);
nodes_.pop_back();
}
#ifdef DEBUG_CBC_HEAP
if (best) {
int n = nodes_.size();
bool good = true;
for (int i = 0; i < n; i++) {
// temp
assert (nodes_[i]);
if (!comparison_.compareNodes(nodes_[i], best)) {
good = false;
CbcNode * x = nodes_[i];
printf("i=%d x is better nun %d depth %d obj %g, best nun %d depth %d obj %g\n", i,
x->numberUnsatisfied(), x->depth(), x->objectiveValue(),
best->numberUnsatisfied(), best->depth(), best->objectiveValue());
}
}
if (!good) {
// compare best to all
int i;
for (i = 0; i < n; i++) {
CbcNode * x = nodes_[i];
printf("i=%d x is nun %d depth %d obj %g", i,
x->numberUnsatisfied(), x->depth(), x->objectiveValue());
if (!comparison_.compareNodes(x, best)) {
printf(" - best is worse!\n");
} else {
printf("\n");
}
}
// Now compare amongst rest
for (i = 0; i < n; i++) {
CbcNode * x = nodes_[i];
printf("For i=%d ", i);
for (int j = i + 1; j < n; j++) {
CbcNode * y = nodes_[j];
if (!comparison_.compareNodes(x, y)) {
printf(" b %d", j);
} else {
printf(" w %d", j);
}
}
printf("\n");
}
assert(good);
}
}
#endif
if (best)
best->setOnTree(false);
return best;
}
/*
Return the best node from the heap.
Note that best is offered a chance (checkIsCutoff) to reevaluate
itself and make arbitrary changes. A caller should be prepared
to check that the returned node is acceptable.
There's quite a bit of suspect code here, much of it disabled in
some way. The net effect at present is to return the top node on
the heap after offering the node an opportunity to reevaluate itself.
Documentation for checkIsCutoff() puts no restrictions on allowable
changes. -- lh, 100921 --
*/
CbcNode *
CbcTree::bestNode(double cutoff)
{
# if CBC_DEBUG_HEAP > 0
validateHeap() ;
# endif
/*
This code is problematic. As of 100921, there's really no loop.
If front() == null, an assert will trigger. checkIsCutoff seems to be
work in progress; comments assert that it can make pretty much arbitrary
changes to best. If best can change its objective, there's a good
possibility the heap is invalid.
*/
CbcNode * best = NULL;
while (!best && nodes_.size()) {
best = nodes_.front();
if (best)
assert(best->objectiveValue() != COIN_DBL_MAX && best->nodeInfo());
if (best && best->objectiveValue() != COIN_DBL_MAX && best->nodeInfo())
assert (best->nodeInfo()->numberBranchesLeft());
if (best && best->objectiveValue() >= cutoff) {
// double check in case node can change its mind!
best->checkIsCutoff(cutoff);
}
if (!best || best->objectiveValue() >= cutoff) {
#ifdef JJF_ZERO
// take off
std::pop_heap(nodes_.begin(), nodes_.end(), comparison_);
nodes_.pop_back();
delete best;
best = NULL;
#else
// let code get rid of it
assert (best);
#endif
}
}
/*
See if the comparison object wants us to do a full scan with the
alternative criteria. The net effect is to confirm best by the
alternative criteria, or identify a competitor and erase it.
This code is problematic. Nulling an arbitrary node will in general
break the heap property. Disabled some time ago, as noted in several
places.
*/
if (false && best && comparison_.test_->fullScan()) {
CbcNode * saveBest = best;
size_t n = nodes_.size();
size_t iBest = -1;
for (size_t i = 0; i < n; i++) {
// temp
assert (nodes_[i]);
assert (nodes_[i]->nodeInfo());
if (nodes_[i] && nodes_[i]->objectiveValue() != COIN_DBL_MAX && nodes_[i]->nodeInfo())
assert (nodes_[i]->nodeInfo()->numberBranchesLeft());
if (nodes_[i] && nodes_[i]->objectiveValue() < cutoff
&& comparison_.alternateTest(best, nodes_[i])) {
best = nodes_[i];
iBest = i;
}
}
if (best == saveBest) {
// can pop
// take off
std::pop_heap(nodes_.begin(), nodes_.end(), comparison_);
nodes_.pop_back();
} else {
// make impossible
nodes_[iBest] = NULL;
}
} else if (best) {
# if CBC_DEBUG_HEAP > 2
CbcNode *node = nodes_.front() ;
CbcNodeInfo *info = node->nodeInfo() ;
assert(info) ;
std::cout
<< " bestNode: Popping node " << node->nodeNumber()
<< "(" << std::hex << node << std::dec
<< ") obj " << node->objectiveValue()
<< ", ref " << info->decrement(0)
<< ", todo " << info->numberBranchesLeft()
<< ", refd by " << info->numberPointingToThis() << "." << std::endl ;
# endif
// take off
std::pop_heap(nodes_.begin(), nodes_.end(), comparison_);
nodes_.pop_back();
}
#if CBC_DEBUG_HEAP > 0
validateHeap() ;
#endif
if (best)
best->setOnTree(false);
return best;
}
