misc

Author: Zanger67

my-submissions/m146 v2 proper DLL.py

@@ -0,0 +1,99 @@
+class DLLNode:
+    def __init__(
+        self,
+        key: int,
+        data: int,
+        prev_node: Optional['DLLNode'] = None,
+        next_node: Optional['DLLNode'] = None
+    ):
+        self.key = key
+        self.data = data
+        self.prev = prev_node
+        self.next = next_node
+
+class LRUCache:
+    def __init__(self, capacity: int):
+        self.head = None
+        self.tail = None
+        self.key2node = {}
+        self.cap = capacity
+        self.size = 0
+
+    def get(self, key: int) -> int:
+        if key not in self.key2node :
+            return -1
+
+        output_data = self.pop(key)
+        self.append_end(key, output_data)
+        return output_data
+
+    def put(self, key: int, value: int) -> None:
+        if key in self.key2node :
+            self.pop(key)
+
+        if self.size >= self.cap :
+            self.pop()
+
+        self.append_end(key, value)
+
+    def append_end(self, key: int, data: int) -> None:
+        new_node = DLLNode(key=key, data=data, prev_node=self.tail)
+        self.key2node[key] = new_node
+        self.size += 1
+
+        # this should apply to both if tail and head doesn't exist
+        # since if at least one node exists, it's both tail and head
+        if not self.tail :
+            self.head = new_node
+            self.tail = new_node
+            return
+
+        self.tail.next = new_node
+        self.tail = new_node
+
+    # Default pop last
+    def pop(self, key: int = None) -> int :
+        if self.size == 0 :
+            return -1
+
+        # Pop LFU node by default
+        if key is None :
+            key = self.head.key
+
+        if key not in self.key2node :
+            return -1
+
+        self.size -= 1
+        popping_node = self.key2node.pop(key)
+        output_data = popping_node.data
+
+        # If it was the only node in DLL
+        if self.size == 0 :
+            self.head = None
+            self.tail = None
+            return output_data
+
+        # if is head
+        if popping_node.prev is None :
+            self.head = popping_node.next
+            if self.head is not None :
+                self.head.prev = None
+            return output_data
+
+        # if is tail
+        if popping_node.next is None :
+            self.tail = popping_node.prev
+            if self.tail is not None :
+                self.tail.next = None
+            return output_data
+
+        # Regular node
+        prev_node, next_node = popping_node.prev, popping_node.next
+        prev_node.next, next_node.prev = next_node, prev_node
+        return output_data
+
+
+# Your LRUCache object will be instantiated and called as such:
+# obj = LRUCache(capacity)
+# param_1 = obj.get(key)
+# obj.put(key,value)