From 1930e31d398817923d87bc63361d0041e1de03dc Mon Sep 17 00:00:00 2001
From: Hamid Gasmi <mamid1706@hotmail.fr>
Date: Thu, 7 Jul 2022 08:18:02 -0700
Subject: [PATCH 1/2] #241: implement lru cache part 1

---
 09-problems/lc_146_lru_cache.py | 40 +++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 09-problems/lc_146_lru_cache.py

diff --git a/09-problems/lc_146_lru_cache.py b/09-problems/lc_146_lru_cache.py
new file mode 100644
index 0000000..6fcf026
--- /dev/null
+++ b/09-problems/lc_146_lru_cache.py
@@ -0,0 +1,40 @@
+class LRU_Cache:
+    def __init__(self, capacity: int):
+        self.__capacity = capacity
+        
+        self.__key_node_dict = {}
+        self.__key_value_dict = {}
+        self.__doubly_linked_list = None
+    
+    def get(self, key: int) -> int:
+        val = self.__dict.get(key, -1)
+        if val == -1:
+            return -1
+        
+        key_node = self.__key_node_dict[key]
+        
+        self.__doubly_linked_list.remove(key_node)
+        self.__doubly_linked_list.add(key_node)
+        
+        return val
+    
+    def put(self, key: int, value: int) -> None:
+        
+        self.__key_value_dict[key] = value
+        
+        if self.__doubly_linked_list.tail.key == key:
+            return
+        
+        key_node = self.__key_node_dict(key, None)
+        if (key_node):
+            self.__doubly_linked_list.remove(key_node)
+            self.__doubly_linked_list.add(key_node)
+            return
+        
+        key_node = Doubly_Linked_Node(key)
+        if len(self.__key_value_dict) > self.__capacity:
+            self.__doubly_linked_list.remove(self.__doubly_linked_list.head)
+        
+        self.__doubly_linked_list.add(key_node)
+        self.__doubly_linked_list[key] = key_node
+    
\ No newline at end of file

From 0d09819b30f07d0a9dc31d6f28666fe051282206 Mon Sep 17 00:00:00 2001
From: Hamid Gasmi <mamid1706@hotmail.fr>
Date: Mon, 11 Jul 2022 06:37:41 -0700
Subject: [PATCH 2/2] #241: implement lru cache

---
 09-problems/lc_146_lru_cache.py | 72 ++++++++++++++++++++++++---------
 1 file changed, 54 insertions(+), 18 deletions(-)

diff --git a/09-problems/lc_146_lru_cache.py b/09-problems/lc_146_lru_cache.py
index 6fcf026..782fb86 100644
--- a/09-problems/lc_146_lru_cache.py
+++ b/09-problems/lc_146_lru_cache.py
@@ -1,40 +1,76 @@
-class LRU_Cache:
+class Doubly_Linked_Node:
+    def __init__(self, key: int):
+        self.prev = None
+        self.next = None
+        self.key = key
+        
+class Doubly_Linked_List:
+    def __init__(self, head: Doubly_Linked_Node, tail: Doubly_Linked_Node):
+        self.head = head
+        self.tail = tail
+    
+    def add(self, node: Doubly_Linked_Node):
+        if self.tail == None:
+            self.head = node
+            self.tail = node
+        
+        else:
+            self.tail.next = node
+            node.prev = self.tail
+            self.tail = node
+    
+    def remove(self, node: Doubly_Linked_Node):
+        if node == self.head == self.tail:
+            self.head = None
+            self.tail = None
+        
+        elif node == self.head:
+            self.head = self.head.next
+            self.head.prev = None
+        
+        elif node == self.tail:
+            self.tail = self.tail.prev
+            self.tail.next = None
+        
+        elif node.prev and node.next:
+            node.prev.next = node.next
+            node.next.prev = node.prev
+
+class LRUCache:
     def __init__(self, capacity: int):
         self.__capacity = capacity
         
         self.__key_node_dict = {}
         self.__key_value_dict = {}
-        self.__doubly_linked_list = None
+        self.__linked_list = Doubly_Linked_List(None, None)
     
     def get(self, key: int) -> int:
-        val = self.__dict.get(key, -1)
+        val = self.__key_value_dict.get(key, -1)
         if val == -1:
             return -1
         
         key_node = self.__key_node_dict[key]
         
-        self.__doubly_linked_list.remove(key_node)
-        self.__doubly_linked_list.add(key_node)
-        
+        self.__linked_list.remove(key_node)
+        self.__linked_list.add(key_node)
+
         return val
     
     def put(self, key: int, value: int) -> None:
         
         self.__key_value_dict[key] = value
         
-        if self.__doubly_linked_list.tail.key == key:
-            return
-        
-        key_node = self.__key_node_dict(key, None)
+        key_node = self.__key_node_dict.get(key, None)
         if (key_node):
-            self.__doubly_linked_list.remove(key_node)
-            self.__doubly_linked_list.add(key_node)
-            return
+            self.__linked_list.remove(key_node)
+        else:
+            key_node = Doubly_Linked_Node(key)
+            self.__key_node_dict[key] = key_node
+        self.__linked_list.add(key_node)
         
-        key_node = Doubly_Linked_Node(key)
         if len(self.__key_value_dict) > self.__capacity:
-            self.__doubly_linked_list.remove(self.__doubly_linked_list.head)
+            self.__key_node_dict.pop(self.__linked_list.head.key)
+            self.__key_value_dict.pop(self.__linked_list.head.key)
+            self.__linked_list.remove(self.__linked_list.head)
         
-        self.__doubly_linked_list.add(key_node)
-        self.__doubly_linked_list[key] = key_node
-    
\ No newline at end of file
+        
\ No newline at end of file