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LRUCache_146.py
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LRUCache_146.py
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#!/usr/bin/env python
# coding=utf-8
class LRUCache(object):
def __init__(self, capacity):
"""
:type capacity: int
"""
self.capacity = capacity
self.number = 0
self.map = dict()
self.head = Node()
self.tail = self.head
def get(self, key):
"""
:rtype: int
"""
if key in self.map:
node = self.map[key]
self.removeNode(node)
self.insertToHead(node)
return node.value
else:
return -1
def set(self, key, value):
"""
:type key: int
:type value: int
:rtype: nothing
"""
if key in self.map:
node = self.map[key]
node.value = value
self.removeNode(node)
self.insertToHead(node)
else:
if self.number == self.capacity:
tail = self.tail
self.removeNode(tail)
self.insertToHead(Node(key, value))
else:
self.insertToHead(Node(key, value))
def removeNode(self, node):
self.number -= 1
del self.map[node.key]
prevNode = node.prev
nextNode = node.next
prevNode.next = nextNode
if nextNode != None:
nextNode.prev = prevNode
if self.head.next == node:
self.head.next = nextNode
if self.tail == node:
self.tail = prevNode
def insertToHead(self, node):
self.number += 1
self.map[node.key] = node
nextNode = self.head.next
self.head.next = node
if nextNode != None:
nextNode.prev = node
node.prev = self.head
node.next = nextNode
if self.tail == self.head:
self.tail = node
class Node(object):
def __init__(self, key = None, value = None):
self.prev = None
self.next = None
self.key = key
self.value = value