问题url
https://leetcode-cn.com/problems/lru-cache/

答案

# -*- coding: utf-8 -*-
cg = "cgnb"
class linknode:
    def __init__(self,key:int,value:int):
        self.key = key
        self.value = value
        self.prenode = None
        self.nextnode = None
class LRUCache:
    def __init__(self, capacity: int):
        self.dict1 = {}
        self.capacity = capacity
        self.headnode = None
        self.lastnode = None      
    def get(self, key: int) -> int:
        if key in self.dict1:
            node = self.dict1[key]
            value = self.dict1[key].value
            pre_node = node.prenode
            next_node = node.nextnode
            if (pre_node is None) & (next_node is None):
                pass
            else:
               if not pre_node is None:
                   if next_node is None:
                      pre_node.nextnode = node
                   else:
                      pre_node.nextnode = next_node
               else :
                   self.headnode = next_node
               if not next_node is None:
                   next_node.prenode = pre_node
            if self.lastnode != node:
               lastnode = self.lastnode
               lastnode.nextnode = node
               node.prenode = lastnode
               node.nextnode = None
               self.lastnode = node
            return value
        else:
            return -1
    def put(self, key: int, value: int) -> None:
        if len(self.dict1) == 0:
            node = linknode(key,value)
            self.dict1[key] = node
            self.headnode = node
            self.lastnode = node
        elif key in self.dict1:
            self.get(key)
            self.dict1[key].value = value
        elif len(self.dict1)<self.capacity:
            node = linknode(key,value)
            self.dict1[key] = node
            node.prenode = self.lastnode
            self.lastnode.nextnode = node
            self.lastnode = node
        else:
            del_key = self.headnode.key
            self.headnode = self.dict1[del_key].nextnode
            del self.dict1[del_key]
            node = linknode(key,value)
            self.dict1[key] = node
            node.prenode = self.lastnode
            self.lastnode.nextnode = node
            self.lastnode = node
        



# Your LRUCache object will be instantiated and called as such:
# obj = LRUCache(capacity)
# param_1 = obj.get(key)
# obj.put(key,value)