标签：
Design and implement a data structure for Least Recently Used (LRU) cache. It should support the following operations: get and set.
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.
Subscribe to see which companies asked this question
1 public class LRUCache 2 { 3 private class Node 4 { 5 Node prev; 6 Node next; 7 int key; 8 int value; 9 10 public Node(int key, int value) 11 { 12 this.key = key; 13 this.value = value; 14 this.prev = null; 15 this.next = null; 16 } 17 } 18 19 private int capacity; 20 private HashMap<Integer, Node> hs = new HashMap<Integer, Node>(); 21 private Node head = new Node(-1, -1); 22 private Node tail = new Node(-1, -1); 23 24 public LRUCache(int capacity) 25 { 26 this.capacity = capacity; 27 tail.prev = head; 28 head.next = tail; 29 } 30 31 public int get(int key) 32 { 33 if( !hs.containsKey(key)) 34 { 35 return -1; 36 } 37 38 // remove current 39 Node current = hs.get(key); 40 node_delete(current); 41 42 // move current to tail 43 move_to_head(current); 44 45 return hs.get(key).value; 46 } 47 48 public void set(int key, int value) 49 { 50 if( get(key) != -1) 51 { 52 hs.get(key).value = value; 53 return; 54 } 55 56 if (hs.size() == capacity) 57 { 58 Node LastNode = tail.prev; 59 hs.remove(LastNode.key); 60 node_delete(LastNode); 61 } 62 63 Node insert = new Node(key, value); 64 hs.put(key, insert); 65 move_to_head(insert); 66 } 67 private void node_delete(Node current) 68 { 69 current.prev.next = current.next; 70 current.next.prev = current.prev; 71 } 72 private void move_to_head(Node node) 73 { 74 node.next = head.next; 75 node.next.prev = node; 76 node.prev = head; 77 head.next = node; 78 } 79 }
标签：
原文地址：http://www.cnblogs.com/ym65536/p/5800742.html
