a Problem 5 - 1TakeInterview

LRU Cache


Design and implement a data structure for Least Recently Used (LRU) cache.

It should support the following operations: get and put.

get(key) - Get the value (will always be positive) of the key if the key exists in the cache, otherwise return -1.

put(key, value) - Set or insert the value if the key is not already present. When the cache reached its capacity, it should invalidate the least recently used item before inserting a new item.


LRUCache cache = new LRUCache( 2 ); -- Takes capacity of cache as an input

cache.put(0, 1);
cache.put(5, 2);
cache.get(0);       // returns 1
cache.put(3, 3);    // evicts key 5
cache.get(5);       // returns -1 (not found)
cache.put(4, 4);    // evicts key 0
cache.get(0);       // returns -1 (not found)
cache.get(3);       // returns 3
cache.get(4);       // returns 4

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