private Set<Integer> getPossibleNumberOfDepartures(
Set<Integer> unvisitedDays,
HashMap<Integer, Set<Integer>> individualVesselDeparturePatterns,
int alreadyVisitedDaysAvailable) {
int maxDeparturesInPattern =
Collections.max(
problemData
.getVesselDeparturePatterns()
.keySet()); // the maximum number of departures found in any vessel pattern
int minimumNumberOfDepartures =
Math.max(
0,
maxDeparturesInPattern
- alreadyVisitedDaysAvailable); // e.g. if the patterns have max 3 visits and only 1
// day that is already visited can be a part of the
// pattern, the minimum pattern size is 2 (since
// there are 2 unvisited days)
Set<Integer> allNumberOfDepartures = problemData.getVesselDeparturePatterns().keySet();
Set<Integer> possibleNumberOfDepartures = new HashSet<Integer>();
for (Integer numberOfDepartures : allNumberOfDepartures) {
if (numberOfDepartures >= minimumNumberOfDepartures) {
possibleNumberOfDepartures.add(numberOfDepartures);
}
}
return possibleNumberOfDepartures;
}
private Set<Integer> pickRandomVesselDeparturePattern(
Set<Integer> daysWithDeparture,
HashMap<Integer, Set<Integer>> individualVesselDeparturePatterns) {
Set<Integer> unvisitedDays =
getUnvisitedDays(
daysWithDeparture,
individualVesselDeparturePatterns); // the set of days that installations require a
// departure and no vessel depart on
int alreadyVisitedDaysAvailable =
getAlreadyVisitedDaysAvailable(
individualVesselDeparturePatterns,
unvisitedDays); // the number of days that already have visits that the vessel pattern
// can contain
Set<Integer> possibleNumberOfDepartures =
getPossibleNumberOfDepartures(
unvisitedDays,
individualVesselDeparturePatterns,
alreadyVisitedDaysAvailable); // the set of number of departures that a valid vessel
// pattern can have, e.g. if it's the last vessel and
// there are still 3 unvisited days, the vessel pattern
// must have 3 depatures
int unvisitedDaysThatNeedsVisit = Collections.min(possibleNumberOfDepartures);
int numberOfVesselDepartures =
Utilities.pickRandomElementFromSet(
possibleNumberOfDepartures); // select a random number from the set of possible number
// of departures
Set<Set<Integer>> allPatternsForNumberOfDepartures =
problemData.getVesselDeparturePatterns().get(numberOfVesselDepartures);
Set<Set<Integer>> possibleVesselDeparturePatterns =
getPossibleVesselPatterns(
allPatternsForNumberOfDepartures,
individualVesselDeparturePatterns,
unvisitedDays,
unvisitedDaysThatNeedsVisit); // get all vessel patterns with the selected number of
// departures that visit enough of the unvisited
// installations, e.g. if it's the last vessel the pattern
// has to visit all unvisited installations
if (possibleVesselDeparturePatterns.size()
== 0) { // workaround until a smarter heuristic is fixed
System.out.println("No possible patterns, start over!");
return null;
}
return Utilities.pickRandomElementFromSet(possibleVesselDeparturePatterns);
}
private int getAlreadyVisitedDaysAvailable(
HashMap<Integer, Set<Integer>> individualVesselDeparturePatterns,
Set<Integer> unvisitedDays) {
int vesselsLeft =
problemData.getVessels().size()
- individualVesselDeparturePatterns.keySet().size(); // number of unchartered vessels
int maxDeparturesInPattern =
Collections.max(
problemData
.getVesselDeparturePatterns()
.keySet()); // the maximum number of departures found in any vessel pattern
int alreadyVisitedDaysAvailable =
(vesselsLeft * maxDeparturesInPattern
- unvisitedDays
.size()); // if there is 1 unchartered vessel and the patterns have maximum 3
// departures and there are 2 days without departures, at most 1*3 - 2 = 1
// day that already has a departure can be part of the new pattern
return alreadyVisitedDaysAvailable;
}
