好吧，今天晚上赶项目确实是做不了三道题目了，最近项目在网络编程方面有些进步，学到了东西，有时间再积累下来，很深的体会就是，和别人一起写代码，虽然蛋疼但是比自己一个人写要好点，不过发现自己对链表和排序什么的都不太熟练啊，得好好认真练习，加油！
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public class LRUCache { private int capacity; private HashMap<Integer, Node> map; private Node firstNode; private Node lastNode; public LRUCache(int capacity) { this.capacity = capacity; firstNode = new Node(); lastNode = new Node(); firstNode.next = lastNode; lastNode.pre = firstNode; map = new HashMap<Integer, Node>(); } public int get(int key) { if (map.containsKey(key)) { Node node = map.get(key); moveToHead(node); return node.value; } else { return -1; } } public void set(int key, int value) { if (map.containsKey(key)) { Node node = map.get(key); node.value = value; moveToHead(node); }else{ if(map.size()>=capacity){ if(lastNode!=null&&capacity>0){ Node dNode = lastNode.pre; lastNode.pre = dNode.pre; dNode.pre.next = lastNode; map.remove(dNode.key); Node node = new Node(); node.key = key; node.value = value; moveToHead(node); map.put(key, node); } }else{ Node node = new Node(); node.key = key; node.value = value; moveToHead(node); map.put(key, node); } } } class Node { Node pre; Node next; int key; int value; } public void moveToHead(Node node) { if (node.next != null&&node.pre != null) { node.pre.next = node.next; node.next.pre = node.pre; } if (firstNode != null) { node.pre = firstNode; node.next = firstNode.next; firstNode.next.pre = node; firstNode.next = node; } } }
原文：http://www.cnblogs.com/youkita/p/3624692.html