import java.util.HashMap; import java.util.HashSet; import java.util.Map; import java.util.Set; public class Potluck { private Map participants; private Map dishes; private Map votes; public Potluck() { participants = new HashMap<>(); dishes = new HashMap<>(); votes = new HashMap<>(); } public boolean addParticipant(String memberId) { if (participants.containsKey(memberId)) { return false; } else { participants.put(memberId, System.currentTimeMillis()); return true; } } public boolean removeParticipant(String memberId) { if (!participants.containsKey(memberId)) { return false; } else { participants.remove(memberId); dishes.remove(memberId); votes.remove(memberId); return true; } } public boolean addDish(String memberId, String dishName) { if (!participants.containsKey(memberId) || dishes.containsKey(memberId)) { return false; } else { dishes.put(memberId, dishName); return true; } } public boolean vote(String memberId, String voteId) { if (participants.containsKey(memberId) && !votes.containsKey(memberId)) { votes.put(memberId, voteId); return true; } else { return false; } } public String dishOfTheDay() { if (votes.isEmpty()) { return null; } // Count votes for each dish Map voteCount = new HashMap<>(); for (String vote : votes.values()) { voteCount.put(vote, voteCount.getOrDefault(vote, 0) + 1); } // Determine maximum votes int maxVotes = voteCount.values().stream().max(Integer::compare).orElse(0); // Collect all dishes with maximum votes Set maxVoteDishes = new HashSet<>(); for (Map.Entry entry : voteCount.entrySet()) { if (entry.getValue() == maxVotes) { maxVoteDishes.add(entry.getKey()); } } // Find the earliest joining time among the tied dishes long earliestJoinTime = Long.MAX_VALUE; String dishOfTheDayMember = null; for (String memberId : maxVoteDishes) { if (participants.get(memberId) < earliestJoinTime) { earliestJoinTime = participants.get(memberId); dishOfTheDayMember = memberId; } } return "Participant: '" + dishOfTheDayMember + "', Dish: '" + dishes.get(dishOfTheDayMember) + "'"; } }