ByteDance Software Engineer Interview Questions

In ByteDance's social networking site, we need to model user relationships and find the most relevant connections for a given user in a depth-first manner.
You are to implement a function that takes the connections of users and a target user, returning all relevant connections.Method Signature: def find_relevant_connections(connections: Dict[str, List[str]], user: str) -> List[str]:
- connections: a dictionary where keys are user IDs and values are lists of user IDs representing friendships.
- user: a string representing the target user's ID.
- Returns a list of user IDs that are reachable from the target user.Example 1:
Input: connections = {'a': ['b', 'c'], 'b': ['d'], 'c': ['e'], 'd': [], 'e': []} and user = 'a'
Output: ['b', 'c', 'd', 'e']
Explanation: From user 'a', you can reach 'b', 'c', 'd', and 'e'.Example 2:
Input: connections = {'x': ['y'], 'y': ['z'], 'z': []} and user = 'x'
Output: ['y', 'z']
Explanation: User 'x' can reach 'y' and 'z'.Constraints:
- 1 <= len(connections) <= 10^4
- Each user ID has at most 100 characters.

In the dynamic environment of ByteDance's content platform, we need to efficiently generate a user feed that displays trending content based on real-time user interactions.
You are to implement a function that takes a list of user interactions (likes or comments) and generates a list of trending content using a sliding window approach.Method Signature: def generate_trending_feed(interactions: List[str], n: int) -> List[str]:
- interactions: a List of strings representing the IDs of content interacted with by a user.
- n: an integer representing the number of trending content items to return.
- Returns a List of strings containing the IDs of the trending content items.Example 1:
Input: interactions = ['a', 'b', 'a', 'c', 'b', 'a']
Output: ['a', 'b', 'c']
Explanation: Item 'a' is interacted with 3 times, 'b' 2 times, and 'c' 1 time.Example 2:
Input: interactions = ['x', 'y', 'y', 'x', 'x', 'z', 'y']
Output: ['x', 'y', 'z']
Explanation: 'x' has 3 interactions, 'y' has 3, and 'z' has 1.Constraints:
- 1 <= len(interactions) <= 10^4
- 1 <= n <= 100
- interactions[i] is a string with length 1 to 100.

For efficient performance on ByteDance's content delivery platform, we need a system that caches frequently accessed user data and drops the least recently used data when the capacity is exceeded.
You are to implement an LRU (Least Recently Used) cache.Class Name: LRUCache
- Method Signature: def __init__(self, capacity: int):
- Initializes the LRU cache with positive size capacity.- Method Signature: def get(self, key: int) -> int:
- Returns the value of the key if the key exists, otherwise returns -1.- Method Signature: def put(self, key: int, value: int) -> None:
- Update or insert the value if the key is not already present. When the cache reaches its capacity, it should invalidate the least recently used item before inserting a new item.Example 1:
Input: LRUCache(2);
cache.put(1, 1);
cache.put(2, 2);
cache.get(1);
Output: 1;Example 2:
Input: cache.put(3, 3); // LRU key was 2, evicts key 2
cache.get(2);
Output: -1;Constraints:
- capacity is a positive integer.
- All keys and values are in the range of 1 to 10000.
- The functions get and put are guaranteed to be called on existing keys.

ByteDance aims to provide users with a highly personalized experience based on their preferences. You need to design a class to manage and query user preferences effectively.Class Name: UserPreferences
- Method Signature: def add_preference(self, category: str, preference: str) -> None
- Adds a preference to the user's profile.- Method Signature: def get_preferences(self, category: str) -> List[str]
- Returns a list of preferences for a given category.- Method Signature: def delete_preference(self, category: str, preference: str) -> None
- Deletes a specific preference from a given category.Example 1:
Input: user_prefs = UserPreferences() ;
user_prefs.add_preference('music', 'rock')
user_prefs.get_preferences('music')
Output: ['rock']Example 2:
Input: user_prefs.add_preference('music', 'pop') ;
user_prefs.get_preferences('music')
Output: ['rock', 'pop']Constraints:
- 1 <= len(category) <= 100
- 1 <= len(preference) <= 100
- The same preference may not be added multiple times within the same category.