problem0355

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355. Design Twitter

题目

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. Your design should support the following methods:

1. postTweet(userId, tweetId): Compose a new tweet.
2. getNewsFeed(userId): Retrieve 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 herself. Tweets must be ordered from most recent to least recent.
3. follow(followerId, followeeId): Follower follows a followee.
4. unfollow(followerId, followeeId): Follower unfollows a followee.

Example:

Twitter twitter = new Twitter();

// User 1 posts a new tweet (id = 5).
twitter.postTweet(1, 5);

// User 1's news feed should return a list with 1 tweet id -> [5].
twitter.getNewsFeed(1);

// User 1 follows user 2.
twitter.follow(1, 2);

// User 2 posts a new tweet (id = 6).
twitter.postTweet(2, 6);

// 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.getNewsFeed(1);

// User 1 unfollows user 2.
twitter.unfollow(1, 2);

// User 1's news feed should return a list with 1 tweet id -> [5],
// since user 1 is no longer following user 2.
twitter.getNewsFeed(1);

解题思路

见程序注释

Documentation

Index

• type Twitter
  • func Constructor() Twitter
  • func (t *Twitter) Follow(followerID int, followeeID int)
  • func (t *Twitter) GetNewsFeed(userID int) []int
  • func (t *Twitter) PostTweet(userID int, tweetID int)
  • func (t *Twitter) Unfollow(followerID int, followeeID int)

Types

type Twitter

type Twitter struct {
	// contains filtered or unexported fields
}

Twitter is twitter user

func Constructor

func Constructor() Twitter

Constructor initialize your data structure here.

func (*Twitter) Follow

func (t *Twitter) Follow(followerID int, followeeID int)

Follow followee. If the operation is invalid, it should be a no-op.

func (*Twitter) GetNewsFeed

func (t *Twitter) GetNewsFeed(userID int) []int

GetNewsFeed retrieve 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 herself. Tweets must be ordered from most recent to least recent.

func (*Twitter) PostTweet

func (t *Twitter) PostTweet(userID int, tweetID int)

PostTweet compose a new tweet.

func (*Twitter) Unfollow

func (t *Twitter) Unfollow(followerID int, followeeID int)

Unfollow follower unfollows a followee. If the operation is invalid, it should be a no-op.