From 65cbc752f5440183b0cbcd63105fa0540dcb0470 Mon Sep 17 00:00:00 2001
From: shaghayeghfar <146011477+shaghayeghfar@users.noreply.github.com>
Date: Wed, 14 Oct 2026 10:19:06 +0100
Subject: [PATCH 1/2] Implement LRU cache is completed

---
 Sprint-2/implement_lru_cache/lru_cache.py | 71 +++++++++++++++++++++++
 1 file changed, 71 insertions(+)

diff --git a/Sprint-2/implement_lru_cache/lru_cache.py b/Sprint-2/implement_lru_cache/lru_cache.py
index e69de29b..cd43c068 100644
--- a/Sprint-2/implement_lru_cache/lru_cache.py
+++ b/Sprint-2/implement_lru_cache/lru_cache.py
@@ -0,0 +1,71 @@
+class Node:
+    def __init__(self, key, value):
+        self.key = key
+        self.value = value
+        self.previous = None
+        self.next = None
+
+
+class LruCache:
+    def __init__(self, limit):
+        if limit <= 0:
+            raise ValueError("Limit must be greater than zero")
+
+        self.limit = limit
+        self.cache = {}
+
+        # Most recently used node is near the head.
+        # Least recently used node is near the tail.
+        self.head = Node(None, None)
+        self.tail = Node(None, None)
+
+        self.head.next = self.tail
+        self.tail.previous = self.head
+
+    def remove_node(self, node):
+        # Connect the node's neighbours to each other.
+        node.previous.next = node.next
+        node.next.previous = node.previous
+
+    def add_to_front(self, node):
+        # Insert the node immediately after the head.
+        node.next = self.head.next
+        node.previous = self.head
+
+        self.head.next.previous = node
+        self.head.next = node
+
+    def get(self, key):
+        if key not in self.cache:
+            return None
+
+        node = self.cache[key]
+
+        # Using a value makes it the most recently used.
+        self.remove_node(node)
+        self.add_to_front(node)
+
+        return node.value
+
+    def set(self, key, value):
+        # If the key already exists, update its value.
+        if key in self.cache:
+            node = self.cache[key]
+            node.value = value
+
+            self.remove_node(node)
+            self.add_to_front(node)
+            return
+
+        # If the cache is full, remove the least recently used node.
+        if len(self.cache) >= self.limit:
+            oldest_node = self.tail.previous
+
+            self.remove_node(oldest_node)
+            del self.cache[oldest_node.key]
+
+        # Create the new node and add it to the front.
+        new_node = Node(key, value)
+
+        self.cache[key] = new_node
+        self.add_to_front(new_node)

From 029cdd8c3c3b7f4dcea90edf9aa006dd3ba21b83 Mon Sep 17 00:00:00 2001
From: shaghayeghfar <146011477+shaghayeghfar@users.noreply.github.com>
Date: Wed, 14 Oct 2026 21:05:45 +0100
Subject: [PATCH 2/2]  changes were done

---
 Sprint-2/implement_lru_cache/lru_cache.py | 57 +++++++++++------------
 1 file changed, 28 insertions(+), 29 deletions(-)

diff --git a/Sprint-2/implement_lru_cache/lru_cache.py b/Sprint-2/implement_lru_cache/lru_cache.py
index cd43c068..9613d148 100644
--- a/Sprint-2/implement_lru_cache/lru_cache.py
+++ b/Sprint-2/implement_lru_cache/lru_cache.py
@@ -1,3 +1,4 @@
+
 class Node:
     def __init__(self, key, value):
         self.key = key
@@ -6,66 +7,64 @@ def __init__(self, key, value):
         self.next = None
 
 
-class LruCache:
-    def __init__(self, limit):
-        if limit <= 0:
-            raise ValueError("Limit must be greater than zero")
-
-        self.limit = limit
-        self.cache = {}
-
-        # Most recently used node is near the head.
-        # Least recently used node is near the tail.
+class DoublyLinkedList:
+    def __init__(self):
         self.head = Node(None, None)
         self.tail = Node(None, None)
 
         self.head.next = self.tail
         self.tail.previous = self.head
 
-    def remove_node(self, node):
-        # Connect the node's neighbours to each other.
-        node.previous.next = node.next
-        node.next.previous = node.previous
-
     def add_to_front(self, node):
-        # Insert the node immediately after the head.
         node.next = self.head.next
         node.previous = self.head
 
         self.head.next.previous = node
         self.head.next = node
 
+    def remove(self, node):
+        node.previous.next = node.next
+        node.next.previous = node.previous
+
+    def remove_last(self):
+        node = self.tail.previous
+        self.remove(node)
+        return node
+
+
+class LruCache:
+    def __init__(self, limit):
+        if limit <= 0:
+            raise ValueError("Limit must be greater than zero")
+
+        self.limit = limit
+        self.cache = {}
+        self.order = DoublyLinkedList()
+
     def get(self, key):
         if key not in self.cache:
             return None
 
         node = self.cache[key]
 
-        # Using a value makes it the most recently used.
-        self.remove_node(node)
-        self.add_to_front(node)
+        self.order.remove(node)
+        self.order.add_to_front(node)
 
         return node.value
 
     def set(self, key, value):
-        # If the key already exists, update its value.
         if key in self.cache:
             node = self.cache[key]
             node.value = value
 
-            self.remove_node(node)
-            self.add_to_front(node)
+            self.order.remove(node)
+            self.order.add_to_front(node)
             return
 
-        # If the cache is full, remove the least recently used node.
         if len(self.cache) >= self.limit:
-            oldest_node = self.tail.previous
-
-            self.remove_node(oldest_node)
+            oldest_node = self.order.remove_last()
             del self.cache[oldest_node.key]
 
-        # Create the new node and add it to the front.
         new_node = Node(key, value)
-
         self.cache[key] = new_node
-        self.add_to_front(new_node)
+        self.order.add_to_front(new_node)