/**
* Merges the rows. This function uses a heuristical approach that guarantiess to merge all rows
* into one if there is no conflict at all. If there are conflicts the heuristic will be
* best-efford but with linear runtime (given a a number of rows).
*
* @param rows Will be altered, if no conflicts occcured this wil have only one element.
*/
private static void mergeAllRowsIfPossible(ArrayList<Row> rows) {
// use fixed seed in order to get consistent results (with random properties)
Random rand = new Random(5711l);
int tries = 0;
// this should be enough to be quite sure we don't miss any optimalization
// possibility
final int maxTries = rows.size() * 2;
// do this loop until we successfully merged everything into one row
// or we give up until too much tries
while (rows.size() > 1 && tries < maxTries) {
// choose two random entries
int oneIdx = rand.nextInt(rows.size());
int secondIdx = rand.nextInt(rows.size());
if (oneIdx == secondIdx) {
// try again if we choose the same rows by accident
continue;
}
Row one = rows.get(oneIdx);
Row second = rows.get(secondIdx);
if (one.merge(second)) {
// remove the second one since it is merged into the first
rows.remove(secondIdx);
// success: reset counter
tries = 0;
} else {
// increase counter to avoid endless loops if no improvement is possible
tries++;
}
}
}
