public class Twitter {
Map<Integer, Set<Integer>> fans = new HashMap<>();
Map<Integer, LinkedList<Tweet>> tweets = new HashMap<>();
int cnt = 0;
public void postTweet(int userId, int tweetId) {
if (!fans.containsKey(userId)) fans.put(userId, new HashSet<>());
fans.get(userId).add(userId);
if (!tweets.containsKey(userId)) tweets.put(userId, new LinkedList<>());
tweets.get(userId).addFirst(new Tweet(cnt++, tweetId));
}
public List<Integer> getNewsFeed(int userId) {
if (!fans.containsKey(userId)) return new LinkedList<>();
PriorityQueue<Tweet> feed = new PriorityQueue<>((t1, t2) -> t2.time - t1.time);
fans.get(userId).stream()
.filter(f -> tweets.containsKey(f))
.forEach(f -> tweets.get(f).forEach(feed::add));
List<Integer> res = new LinkedList<>();
while (feed.size() > 0 && res.size() < 10) res.add(feed.poll().id);
return res;
}
public void follow(int followerId, int followeeId) {
if (!fans.containsKey(followerId)) fans.put(followerId, new HashSet<>());
fans.get(followerId).add(followeeId);
}
public void unfollow(int followerId, int followeeId) {
if (fans.containsKey(followerId) && followeeId != followerId) fans.get(followerId).remove(followeeId);
}
class Tweet {
int time;
int id;
Tweet(int time, int id) {
this.time = time;
this.id = id;
}
}
}
Processed:
0.009, SQL:
8
