_seq<intT> setCover(Graph GS) {
double epsilon = 0.01;
intT m = maxElt(GS);
cout << "m = " << m << endl;
bucketTime.start();
pair<bucket*, int> B = putInBuckets(GS, epsilon);
bucketTime.stop();
bucket* allBuckets = B.first;
int numBuckets = B.second;
set* S = newA(set, GS.n); // holds sets for current bucket
set* ST = newA(set, GS.n); // temporarily S (pack is not inplace)
int l = 0; // size of S
bool* flag = newA(bool, GS.n);
intT* inCover = newA(intT, GS.n);
intT nInCover = 0;
intT totalWork = 0;
intT* elts = newA(intT,m);
intT threshold = GS.n;
for (int i = 0; i < m; i++) elts[i] = INT_MAX;
// loop over all buckets, largest degree first
for (int i = numBuckets-1; i >= 0; i--) {
bucket currentB = allBuckets[i];
intT degreeThreshold = ceil(pow(1.0+epsilon,i));
if (degreeThreshold == threshold && currentB.n == 0) continue;
else threshold = degreeThreshold;
packTime.start();
// pack leftover sets that are below threshold down for the next round
for (int j = 0; j < l; j++)
flag[j] = (S[j].degree > 0 && S[j].degree < threshold);
intT ln = sequence::pack(S, ST, flag, l);
// pack leftover sets greater than threshold above for this round
for (int j = 0; j < l; j++)
flag[j] = (S[j].degree >= threshold);
intT lb = sequence::pack(S, ST+ln, flag, l);
// copy prebucketed bucket i to end, also for this round
for (int j = 0; j < currentB.n; j++)
ST[j+ln+lb] = currentB.S[j];
lb = lb + currentB.n; // total number in this round
l = ln + lb; // total number including those for next round
swap(ST,S); // since pack is not in place
set* SB = S + ln; // pointer to bottom of sets for this round
packTime.stop();
if (lb > 0) { // is there anything to do in this round?
manisTime.start();
intT work = processBucket(SB, elts, lb, threshold);
totalWork += work;
manisTime.stop();
packTime.start();
// check which sets were selected by manis to be in the set cover
for (int j = 0; j < lb; j++)
flag[j] = SB[j].degree < 0;
// add these to inCover and label by their original ID
int nNew = sequence::packIndex(inCover+nInCover, flag, lb);
for (int j = nInCover; j < nInCover + nNew; j++)
inCover[j] = SB[inCover[j]].id;
nInCover = nInCover + nNew;
packTime.stop();
cout << "i = " << i << " bc = " << currentB.n << " l = " << l << " lb = " << lb
<< " work = " << work << " new = " << nNew << " threshold = " << threshold << endl;
}
}
cout << "Set cover size = " << nInCover << endl;
cout << "Total work = " << totalWork << endl;
cout << "Bucket Time = " << bucketTime.total() << endl;
cout << "Manis Time = " << manisTime.total() << endl;
cout << "Pack Time = " << packTime.total() << endl;
free(elts);
free(S);
free(ST);
free(flag);
freeBuckets(allBuckets);
return _seq<intT>(inCover, nInCover);
}
