Airbnb Software Engineer System Design Questions

Airbnb needs to optimize its API by implementing a caching mechanism for property listings to reduce database load and improve response time.
Problem statement: Implement an LRU (Least Recently Used) cache with a specified capacity. The cache should support get(key) and put(key, value) operations.

• class LRUCache:


• def __init__(self, capacity: int): - Initializes the LRUCache with the maximum capacity.


• def get(self, key: int) -> int: - Returns the value of the key if the key exists in the cache, otherwise return -1.


• def put(self, key: int, value: int): - Update the value of the key if it exists, otherwise add the key-value pair to the cache. When the cache reaches its capacity, it should invalidate the least recently used item before inserting a new item.

Example 1:
Input:
cache = LRUCache(2)
cache.put(1, 1)
cache.put(2, 2)
cache.get(1) // returns 1
cache.put(3, 3) // evicts key 2
cache.get(2) // returns -1 (not found)Example 2:
Input:
cache.put(4, 4) // evicts key 1
cache.get(1) // returns -1 (not found)
cache.get(3) // returns 3
cache.get(4) // returns 4Constraints:

• 1 <= capacity <= 3000


• 0 <= key <= 10^4


• 0 <= value <= 10^4