What is the optimal time complexity of solving Design Twitter?

The optimized solution achieves a time complexity of O(n) by using sorting, mathematical shortcuts, or hash table lookups.

What is the auxiliary space complexity for Design Twitter?

The space complexity is O(1) since we only use a minimal/constant amount of extra memory for tracking variables (or auxiliary space if dynamic structures are allocated).

What are the typical edge cases we must handle in Design Twitter?

Key edge cases include empty collections, negative or large bounds causing integer overflow, arrays with only one element, or inputs where target criteria are not met.

How can we optimize the brute force approach for Design Twitter?

Brute force methods often inspect all possible combinations. We optimize this by sorting the input list to enable binary search, or tracking processed items in a set to avoid redundant nested loop lookups.

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Design Twitter

Learn how to solve the 'Design Twitter' problem. This detailed resource details brute force and optimized approaches.

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Problem Statement

Easy

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.

- postTweet(userId: int, tweetId: int) Composes a new tweet with ID tweetId by the user userId.

- getNewsFeed(userId: int) -> List[int] Retrieves the 10 most recent tweet IDs in the user's news feed.

- follow(followerId: int, followeeId: int) The user with ID followerId started following the user with ID followeeId.

- unfollow(followerId: int, followeeId: int) The user with ID followerId started unfollowing the user with ID followeeId.

Input is a list of operations and arguments. Implement a function twitter(operations: list, arguments: list) -> list that returns a list of results (None for constructor/postTweet/follow/unfollow, and List[int] for getNewsFeed).

Constraints

•1 <= userId, followerId, followeeId <= 500
•0 <= tweetId <= 10^4
•All the tweets have unique IDs
•At most 30000 calls will be made in total

Examples

Example 1

Input

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

Output

[None, None, [5], None, None, [6, 5], None, [5]]

Explanation

User 1 posts tweet 5. News feed: [5]. User 1 follows 2. User 2 posts tweet 6. News feed: [6, 5]. User 1 unfollows 2. News feed: [5].

Need a Hint?

Analyze the input constraints. Try sorting first (O(n log n)) or using a hash map/set to track seen elements in O(n) time.

Edge Cases to Watch

Empty list or null input variables
Single item lists/arrays
Extremely large input bounds causing integer or stack overflow

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