From 9e6f685546302e4b83195cbc2d8ad92aa4b041c1 Mon Sep 17 00:00:00 2001
From: shreefAhmedM <livecoding.33@gmail.com>
Date: Wed, 14 Oct 2026 15:58:39 +0100
Subject: [PATCH 1/2] Implement a cache in Python with an LRU

---
 Sprint-2/implement_lru_cache/lru_cache.py | 62 +++++++++++++++++++++++
 1 file changed, 62 insertions(+)

diff --git a/Sprint-2/implement_lru_cache/lru_cache.py b/Sprint-2/implement_lru_cache/lru_cache.py
index e69de29b..4d0a1b6e 100644
--- a/Sprint-2/implement_lru_cache/lru_cache.py
+++ b/Sprint-2/implement_lru_cache/lru_cache.py
@@ -0,0 +1,62 @@
+
+class _Node:
+    def __init__(self, key=None, value=None):
+        self.key = key
+        self.value = value
+        self.prev = 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 = {}
+        self.head = _Node()
+        self.tail = _Node()
+
+        self.head.next = self.tail
+        self.tail.prev = self.head
+
+    def _remove(self, node):
+        node.prev.next = node.next
+        node.next.prev = node.prev
+
+    def _add_to_front(self, node):
+        node.prev = self.head
+        node.next = self.head.next
+
+        self.head.next.prev = node
+        self.head.next = node
+
+    def _mark_as_used(self, node):
+        self._remove(node)
+        self._add_to_front(node)
+
+    def get(self, key):
+        node = self.cache.get(key)
+
+        if node is None:
+            return None
+
+        self._mark_as_used(node)
+        return node.value
+
+    def set(self, key, value):
+        node = self.cache.get(key)
+
+        if node is not None:
+            node.value = value
+            self._mark_as_used(node)
+            return
+
+        node = _Node(key, value)
+        self.cache[key] = node
+        self._add_to_front(node)
+
+        if len(self.cache) > self.limit:
+            lru_node = self.tail.prev
+            self._remove(lru_node)
+            del self.cache[lru_node.key]
\ No newline at end of file

From ce52e53fa71271695f3fa0ff7a017982102374f2 Mon Sep 17 00:00:00 2001
From: shreefAhmedM <livecoding.33@gmail.com>
Date: Fri, 16 Oct 2026 17:31:47 +0100
Subject: [PATCH 2/2] Refactor LRU cache to use OrderedDict

---
 Sprint-2/implement_lru_cache/lru_cache.py | 53 +++++------------------
 1 file changed, 10 insertions(+), 43 deletions(-)

diff --git a/Sprint-2/implement_lru_cache/lru_cache.py b/Sprint-2/implement_lru_cache/lru_cache.py
index 4d0a1b6e..5da2108f 100644
--- a/Sprint-2/implement_lru_cache/lru_cache.py
+++ b/Sprint-2/implement_lru_cache/lru_cache.py
@@ -1,10 +1,5 @@
 
-class _Node:
-    def __init__(self, key=None, value=None):
-        self.key = key
-        self.value = value
-        self.prev = None
-        self.next = None
+from collections import OrderedDict
 
 
 class LruCache:
@@ -13,50 +8,22 @@ def __init__(self, limit):
             raise ValueError("limit must be greater than zero")
 
         self.limit = limit
-        self.cache = {}
-        self.head = _Node()
-        self.tail = _Node()
-
-        self.head.next = self.tail
-        self.tail.prev = self.head
-
-    def _remove(self, node):
-        node.prev.next = node.next
-        node.next.prev = node.prev
-
-    def _add_to_front(self, node):
-        node.prev = self.head
-        node.next = self.head.next
-
-        self.head.next.prev = node
-        self.head.next = node
-
-    def _mark_as_used(self, node):
-        self._remove(node)
-        self._add_to_front(node)
+        self.cache = OrderedDict()
 
     def get(self, key):
-        node = self.cache.get(key)
-
-        if node is None:
+        if key not in self.cache:
             return None
 
-        self._mark_as_used(node)
-        return node.value
+        self.cache.move_to_end(key)
+        return self.cache[key]
 
     def set(self, key, value):
-        node = self.cache.get(key)
-
-        if node is not None:
-            node.value = value
-            self._mark_as_used(node)
+        if key in self.cache:
+            self.cache[key] = value
+            self.cache.move_to_end(key)
             return
 
-        node = _Node(key, value)
-        self.cache[key] = node
-        self._add_to_front(node)
+        self.cache[key] = value
 
         if len(self.cache) > self.limit:
-            lru_node = self.tail.prev
-            self._remove(lru_node)
-            del self.cache[lru_node.key]
\ No newline at end of file
+            self.cache.popitem(last=False)