What is LRU Cache and how do I use it?

Can you explain what an LRU Cache is?

An LRU Cache, or Least Recently Used Cache, is a data structure that stores a limited number of items and evicts the least recently accessed item when it reaches its capacity.

How do I implement an LRU Cache in Python?

You can use the collections.OrderedDict to maintain the order of access. When you access an item, move it to the end of the dictionary. If the cache exceeds its limit, remove the first item.

Can you show me a code example?

Sure! Here's a simple implementation:

from collections import OrderedDict

class LRUCache:
    def __init__(self, capacity: int):
        self.cache = OrderedDict()
        self.capacity = capacity

    def get(self, key: int) -> int:
        if key not in self.cache:
            return -1
        else:
            self.cache.move_to_end(key)
            return self.cache[key]

    def put(self, key: int, value: int) -> None:
        if key in self.cache:
            self.cache.move_to_end(key)
        self.cache[key] = value
        if len(self.cache) > self.capacity:
            self.cache.popitem(last=False)

What are the advantages of using an LRU Cache?

The main advantages are improved performance by reducing access time for frequently used items and efficient memory usage by evicting less used items.