import pytest

# 链表
class ListNode:
    def __init__(self, val=0, next=None):
        self.val = val
        self.next = next

# 数组转链表
def arr_to_linklist(arr):

    p = None
    for n in reversed(arr):
        node = ListNode(n)
        node.next = p
        p = node
    return p

# 链表转数组
def linkList_to_arr(head):
    res = []
    cur = head
    while cur is not None:
        res.append(cur.val)
        cur = cur.next

    return res

# 数组转链表
def list_to_linklist(arr):
    head = ListNode(arr[0])
    p = head
    for i in range(1, len(arr)):
        p.next = ListNode(arr[i])
        p = p.next
    return head