Initial File

netsetos · web-flow · commit dbfa04df4870 · 2020-03-01T20:19:07.000+05:30
LRU Cache Implementations
diff --git a/lru_cache.py b/lru_cache.py
@@ -0,0 +1,62 @@
+class Node:
+    def __init__(self, k, v):
+        self.key = k
+        self.value = v
+        self.next = None
+        self.prev = None
+
+
+class LRU_cache:
+    def __init__(self, capacity):
+        self.capacity = capacity
+        self.dic = dict()
+
+        self.head = Node(0, 0)
+        self.tail = Node(0, 0)
+        self.head.next = self.tail
+        self.tail.prev = self.head
+
+
+
+    def _add(self, node):
+        p = self.tail.prev
+        p.next = node
+        self.tail.prev = node
+        node.next = self.tail
+        node.prev = p
+
+
+    def _remove(self, node):
+        p = node.prev
+        n = node.next
+        p.next = n
+        n.prev = p
+
+
+
+    def get(self, key):
+        if key in self.dic:
+            n = self.dic[key]
+            self._remove(n)
+            self._add(n)
+            return n.value
+        return -1
+
+    def set(self, key, value):
+        n = Node(key, value)
+        self._add(n)
+        self.dic[key] = n
+        if len(self.dic) > self.capacity:
+            n = self.head.next
+            self._remove(n)
+            del self.dic[n.key]
+
+
+cache = LRU_cache(3)
+
+cache.set('a', 'apple')
+cache.set('b', 'ball')
+cache.set('c', 'cat')
+cache.set('d', 'dog')
+print(cache.get('a'))
+print(cache.get('c'))
