adding lru cache optmizer functionality

Author: Cédrick Chaud

lru_cache.py

@@ -0,0 +1,61 @@
+class Node:
+    def __init__(self, key, value):
+        self.key = key
+        self.value = value
+        self.prev = None
+        self.next = None
+
+class LRUCache(object):
+
+    def __init__(self, capacity):
+        """
+        :type capacity: int
+        """
+        self.capacity = capacity
+        self.dict = dict()
+        self.head = Node(0, 0)
+        self.tail = Node(0, 0)
+        self.head.next = self.tail
+        self.tail.prev = self.head 
+        
+    def remove(self, node):
+        prev = node.prev
+        next = node.next
+        prev.next = next
+        next.prev = prev
+        
+    def add(self, node):
+        prev = self.tail.prev
+        prev.next = node
+        self.tail.prev = node
+        node.prev = prev
+        node.next = self.tail
+        
+    def get(self, key):
+        """
+        :type key: int
+        :rtype: int
+        """
+        if key in self.dict:
+            node = self.dict[key]
+            self.remove(node)
+            self.add(node)
+            return node.value
+        return -1
+        
+
+    def put(self, key, value):
+        """
+        :type key: int
+        :type value: int
+        :rtype: void
+        """
+        if key in self.dict:
+            self.remove(self.dict[key])
+            node = Node(key, value)
+            self.add(node)
+            self.dict[key] = node
+            if len(self.dict) > self.capacity:
+                node = self.head.next
+                self.remove(node)
+                del self.dict[node.key]

test_for_lru_cache.py

@@ -0,0 +1,6 @@
+from lru_cache import *
+
+# Your LRUCache object will be instantiated and called as such:
+# obj = LRUCache(capacity)
+# param_1 = obj.get(key)
+# obj.put(key,value)