static int calculateH(final ArrayList<Integer> counts) {
int h = 0;
for (int i = 0; i < counts.size() - 1; i++) {
for (int j = i + 1; j < counts.size(); j++) {
h += counts.get(i) * counts.get(j);
}
}
return h;
}
int calculateH(Cluster cluster) {
final Map<Object, Integer> documentCountByPartition =
getDocumentCountByPartition(cluster.getAllDocuments());
final ArrayList<Integer> counts = Lists.newArrayList();
counts.addAll(documentCountByPartition.values());
return calculateH(counts);
}
static int calculateWorstCaseH(int clusterSize, int partitionCount) {
final ArrayList<Integer> counts = Lists.newArrayList();
for (int partition = 0; partition < partitionCount; partition++) {
counts.add(
clusterSize / partitionCount + (partition < (clusterSize % partitionCount) ? 1 : 0));
}
return calculateH(counts);
}