【专项训练】数组、链表
数组array：
list = []
链表linked list
# Definition for singly-linked list.
class ListNode:def __init__(self, x):self.val = xself.next = 
数组array：
list = []
链表linked list
# Definition for singly-linked list.
class ListNode:def __init__(self, x):self.val = xself.next =