LRU Cache

lru_cache.py

from collections import OrderedDict
class LRUCache:

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

    def get(self, key: int) -> int:
        val = -1
        if key in self.cache:
            val = self.cache[key]
            del self.cache[key]
            self.cache[key] = val
        return val

    def put(self, key: int, value: int) -> None:
        if key in self.cache:
            del self.cache[key]
        elif self.capacity == len(self.cache):
            oldest = next(iter(self.cache))
            del self.cache[oldest]
        self.cache[key] = value