0146.py

import collections
class LRUCache:
    def __init__(self, capacity):
        """
        :type capacity: int
        """
        self.capacity = capacity
        self.cache = collections.OrderedDict()

    def get(self, key):
        """
        :type key: int
        :rtype: int
        """
        if key in self.cache:
            value = self.cache.pop(key)
            self.cache[key] = value
            return value
            
        return -1

    def put(self, key, value):
        """
        :type key: int
        :type value: int
        :rtype: void
        """
        if key in self.cache:
            self.cache.pop(key)
        else:
            if len(self.cache) == self.capacity:
                self.cache.popitem(last=False)
                
        self.cache[key] = value