@Override
public Pair<ExpandingArrayList<Long>, Long> treeReduce(
Pair<ExpandingArrayList<Long>, Long> lhs, Pair<ExpandingArrayList<Long>, Long> rhs) {
ExpandingArrayList<Long> nt = new ExpandingArrayList<Long>();
nt.addAll(lhs.first);
int index = 0;
for (Long l : rhs.first) {
if (nt.get(index) == null) nt.add(l);
else nt.set(index, nt.get(index) + l);
index++;
}
return new Pair<ExpandingArrayList<Long>, Long>(nt, lhs.second + rhs.second);
}
private void updateCounts(ExpandingArrayList<Long> counts, long nRods, long nObs) {
if (nRods >= 0) {
long prev = counts.get((int) nRods) == null ? 0l : counts.get((int) nRods);
counts.set((int) nRods, nObs + prev);
}
}