使用 python3 实现一个链表

class ListNode: def __init__(self, val): self.val = val self.next = None class MyLinkedList: def __init__(self): self.size = 0 # 链表长度 self.head = ListNode(0) def get(self, index: int) -> int: cur = self.head if index < 0 or index >= self.size: return -1 for _ in range(index+1): cur = cur.next return cur.val def addAtHead(self, val: int) -> None: ''' add_head = ListNode(val) add_head.next = self.head self.head = add_head ''' self.addAtIndex(0, val) def addAtTail(self, val: int) -> None: ''' add_end = ListNode(val) cur = self.head while cur.next: cur = cur.next cur.next = add_end ''' self.addAtIndex(self.size, val) def addAtIndex(self, index: int, val: int) -> None: add_node = ListNode(val) cur = self.head if index > self.size: return elif index < 0: # 头部插入 index = 0 self.size += 1 for _ in range(index): cur = cur.next add_node.next = cur.next cur.next = add_node def deleteAtIndex(self, index: int) -> None: cur = self.head if index < 0 or index >= self.size: return self.size -= 1 for _ in range(index): cur = cur.next cur.next = cur.next.next