LinkedIn Software Engineer System Design Questions

LinkedIn needs a feature similar to Twitter feeds, where users can see recent activities of their connections. This involves multiple classes coordinating data retrieval and display.
Problem statement: Design a class TwitterFeed that handles user activity feeds and allows users to follow/unfollow other users.
- Input: Methods to postTweet(userId: int, tweet: str), getNewsFeed(userId: int), follow(followerId: int, followeeId: int), and unfollow(followerId: int, followeeId: int).
- Output: List[str] for getNewsFeed, containing up to 10 most recent tweets from the user and their followed users.
- Constraints:
- UserIds are in the range of 1 to 10^4
- Tweet content can be up to 140 characters.

To enhance performance, LinkedIn requires a caching system that follows the LRU (Least Recently Used) principle for user profile data retrieval.
Problem statement: Design and implement a class LRUCache that supports the following operations:
- get(key: int) -> int: Returns the value of the key if the key exists, otherwise return -1.
- put(key: int, value: int): Update the value of the key if the key exists, or add the key-value pair if the key does not exist. When the cache reaches its capacity, it should invalidate the least recently used item before inserting a new item.
- Input: capacity - maximum number of items the cache can hold.
- Output: int for get, no output for put.Example 1:
Input: ["LRUCache", "put", "put", "get", "put", "get", "get", "put", "get"], [[2], [1, 1], [2, 2], [1], [3, 3], [2], [4], [1], [3]]
Output: [null, null, null, 1, null, 2, -1, null, 3]
Explanation: The cache operates under the mentioned rules and examples.Constraints:
- 1 <= capacity <= 3000
- 0 <= key, value <= 10^4