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.

import java.util.HashMap;
import java.util.LinkedList;



class ListNode{
	int key, value;
	ListNode next, prev;
	public ListNode()
	{
		this.key = this.value = http://www.mamicode.com/0;>