Ruby

1class LRUCache
2  def initialize(capacity)
3    @capacity = capacity
4    @cache = {}
5  end
6
7  def get(key)
8    return -1 if @cache[key] == nil
9
10    value = @cache[key]
11    @cache.delete(key)
12    @cache[key] = value
13    @cache.shift if @cache.length > @capacity
14    return value
15  end
16
17  def put(key, value)
18    @cache.delete(key)
19    @cache[key] = value
20    @cache.shift if @cache.length > @capacity
21  end
22end