LRU Cache

https://leetcode.com/problems/lru-cache/

class Node:
    def __init__(self,k,v):
        self.key = k
        self.val = v
        self.next = None
        self.prev = None
        
class LRUCache:

    def __init__(self, capacity: int):
        self.capacity = capacity
        self.head = Node(0,0)
        self.tail = Node(0,0)
        self.d = dict()
        self.head.next = self.tail
        self.tail.prev = self.head
        

    def get(self, key: int) -> int:
        if key in self.d:
            node = self.d[key]
            self.__remove(node)
            self.__add(node)
            return node.val
        return -1

    def put(self, key: int, value: int) -> None:
        node = Node(key,value)
        if key in self.d:
            self.__remove(self.d[key])
        self.__add(node)
        self.d[key] = node
        if len(self.d) > self.capacity:
            curr = self.head.next
            self.__remove(curr)
            del self.d[curr.key]
    
    
    def __remove(self,node):
        prev = node.prev
        nxt = node.next
        prev.next = nxt
        nxt.prev = prev
    
    
    def __add(self,node):
        p = self.tail.prev
        p.next = node
        node.prev = p
        node.next = self.tail
        self.tail.prev = node