LRU Cache — Medium Coding Interview Question

Design a data structure that follows the constraints of a Least Recently Used (LRU) cache. Implement the LRUCache class: - LRUCache(capacity) Initialize the LRU cache with positive size capacity. - get(key) Return the value of the key if the key exists, otherwise return -1. - put(key, value) Update the value of the key if the key exists. Otherwise, add the key-value pair to the cache. If the number of keys exceeds the capacity from this operation, evict the least recently used key. The functions get and put must each run in O(1) average time complexity.

Example

Input: LRUCache cache = new 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

Output: 1, -1

Constraints

1 <= capacity <= 3000
0 <= key <= 10^4
0 <= value <= 10^5
At most 2 * 10^5 calls will be made to get and put.

Topics & Companies

Topics: hash-map, linked-list

Asked by: Amazon, Google, Microsoft, Meta, Bloomberg

Optimal Solution Complexity

Time complexity: O(1). Space complexity: O(n).