Package g0301_0400.s0355_design_twitter

Class Twitter

java.lang.Object
g0301_0400.s0355_design_twitter.Twitter
public class Twitter extends java.lang.Object
355 - Design Twitter.

Medium

Design a simplified version of Twitter where users can post tweets, follow/unfollow another user, and is able to see the 10 most recent tweets in the user’s news feed.

Implement the Twitter class:

  • Twitter() Initializes your twitter object.
  • void postTweet(int userId, int tweetId) Composes a new tweet with ID tweetId by the user userId. Each call to this function will be made with a unique tweetId.
  • List<Integer> getNewsFeed(int userId) Retrieves the 10 most recent tweet IDs in the user’s news feed. Each item in the news feed must be posted by users who the user followed or by the user themself. Tweets must be ordered from most recent to least recent.
  • void follow(int followerId, int followeeId) The user with ID followerId started following the user with ID followeeId.
  • void unfollow(int followerId, int followeeId) The user with ID followerId started unfollowing the user with ID followeeId.

Example 1:

Input

 ["Twitter", "postTweet", "getNewsFeed", "follow", "postTweet", "getNewsFeed", "unfollow", "getNewsFeed"]
 [ [], [1, 5], [1], [1, 2], [2, 6], [1], [1, 2], [1]]

Output:

 [null, null, [5], null, null, [6, 5], null, [5]]

Explanation:

 Twitter twitter = new Twitter();
 twitter.postTweet(1, 5); // User 1 posts a new tweet (id = 5).
 twitter.getNewsFeed(1); // User 1's news feed should return a list with 1 tweet id -> [5]. return [5]
 twitter.follow(1, 2); // User 1 follows user 2.
 twitter.postTweet(2, 6); // User 2 posts a new tweet (id = 6).
 twitter.getNewsFeed(1); // User 1's news feed should return a list with 2 tweet ids -> [6, 5].
   // Tweet id 6 should precede tweet id 5 because it is posted after tweet id 5.
 twitter.unfollow(1, 2); // User 1 unfollows user 2.
 twitter.getNewsFeed(1); // User 1's news feed should return a list with 1 tweet id -> [5], since user 1 is no longer following user 2.

Constraints:

  • 1 <= userId, followerId, followeeId <= 500
  • 0 <= tweetId <= 104
  • All the tweets have unique IDs.
  • At most 3 * 104 calls will be made to postTweet, getNewsFeed, follow, and unfollow.

  • Constructor Summary

    Constructors
    Constructor
    Description
    Twitter()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    checkNewUser(int userId)
     
    void
    follow(int followerId, int followeeId)
     
    java.util.List<java.lang.Integer>
    getNewsFeed(int userId)
     
    void
    postTweet(int userId, int tweetId)
     
    void
    unfollow(int followerId, int followeeId)
     

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • Twitter

      public Twitter()

  • Method Details

    • postTweet

      public void postTweet(int userId, int tweetId)

    • getNewsFeed

      public java.util.List<java.lang.Integer> getNewsFeed(int userId)

    • follow

      public void follow(int followerId, int followeeId)

    • unfollow

      public void unfollow(int followerId, int followeeId)

    • checkNewUser

      public void checkNewUser(int userId)