LRUCache

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.

Helpful graph and article:

http://www.programcreek.com/2013/03/leetcode-lru-cache-java/

Most common solution : by doubly linkedlist and hash map

http://www.cnblogs.com/feiling/p/3426967.html

In java, by LinkedHashMap:

http://pastebin.com/Y9XcwX0x#