[LeetCode]LRU Cache

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

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.

public class LRUCache {class Node{int key;int val;Node pre;Node next;Node(int key,int val){this.key = key;this.val = val;}}Node head = new Node(-1,-1);Node tail = new Node(-1,-1);private void moveToTail(Node no){this.removeNode(no);no.pre = tail.pre;no.next = tail;tail.pre.next = no;tail.pre = no;}private void addNode(Node no){no.pre = tail.pre;no.next = tail;tail.pre.next = no;tail.pre = no;}private void removeNode(Node no){no.pre.next = no.next;no.next.pre = no.pre;}private Node getHead(){return head.next;}Map<Integer,Node> map = new HashMap<>();int cap;int count = 0;public LRUCache(int capacity) {cap = capacity;head.next = tail;tail.pre = head;}public int get(int key) {Node res = map.get(key);if(res == null) {return -1;}else{int val = res.val;this.moveToTail(res);return val;}}public void set(int key, int value) {if(map.containsKey(key)){Node res = map.get(key);res.val = value;this.moveToTail(res);}else{count++;if(count>cap){Node rem = this.getHead();map.remove(rem.key);rem.key = key;rem.val = value;this.moveToTail(rem);map.put(key, rem);}else{Node nod = new Node(key,value);this.addNode(nod);map.put(key, nod);}}}}

，爱情从希望开始，也由绝望结束。死心了，