| class DNode: | |
| __slots__ = ("key", "value", "prev", "next") | |
| class LRUCache(object): | |
| def __init__(self, capacity): | |
| self.cap = capacity | |
| self.root = DNode() | |
| self.root.next, self.root.prev = self.root, self.root | |
| self.root.key = self.root.value = -1 | |
| self.cache = {} | |
| def move_to_end(self, node: DNode): | |
| node.next.prev, node.prev.next = node.prev, node.next | |
| node.prev, node.next = self.root.prev, self.root | |
| self.root.prev.next, self.root.prev = node, node | |
| def get(self, key: int): | |
| if key not in self.cache: | |
| return -1 | |
| node = self.cache[key] | |
| self.move_to_end(node) | |
| return node.value | |
| def put(self, key: int, value: int): | |
| if key in self.cache: | |
| self.cache[key].value = value | |
| self.move_to_end(self.cache[key]) | |
| else: | |
| if len(self.cache) < self.cap: | |
| node = DNode() | |
| node.key, node.value = key, value | |
| node.prev, node.next = self.root.prev, self.root | |
| self.root.prev.next, self.root.prev = node, node | |
| self.cache[key] = node | |
| else: | |
| self.root.key = key | |
| self.root.value = value | |
| self.cache[key] = self.root | |
| self.cache.pop(self.root.next.key) | |
| self.root = self.root.next | |