【leetcode】LRU Cache

题目简述：

Design and implement a data structure for Least Recently Used (LRU) cache. It should support the following operations: get and set.

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

解题思路：

用一个队列存放当前的元素，用字典结构表示cache

coding=utf-8

class LRUCache:

@param capacity, an integer

def init(self, capacity):
self.cap = capacity
self.cache = {}
self.sta = []

@return an integer

def get(self, key):
if key in self.cache:
self.sta.remove(key)
self.sta.append(key)
return self.cache[key]
else:
return -1

@param key, an integer

@param value, an integer

@return nothing

def set(self, key, value):
if self.cap == len(self.cache) and (key not in self.cache):
self.cache.pop(self.sta[0])
self.sta.pop(0)
if key in self.cache:
self.sta.remove(key)
self.sta.append(key)
else:
self.sta.append(key)
self.cache[key] = value