pythonチェーンテーブル-チェーンテーブルの最後からk番目のノードを見つけます

入力:1->2->3->4->5->6->7、k=3
出力:ノード5
考え方:

  1：      ，         size，      size-k   ，cur.next       
  2：      k        cur1, cur2， cur2.next None ，cur1      k   

コード:

def get_data(head, k):
    if head is None:
        print("The link is None")
        return
    size = 0
    cur = head
    while cur:
        size += 1
        cur = cur.next
    if k <= size:
        index = size - k
        cur2 = head
        count = 0
        #  count=index     ，index      cur2 ，k index    ，k    cur2.next ，     ，          
        while count < index:
            count += 1
            cur2 = cur2.next
        return cur2
    else:
        print(k, "is out of index")


def get_data2(head, k):
    if head is None:
        print("The link is None")
        return
    if k <= 0:
        print(k, " is invalid value")
        return
    cur1 = head
    cur2 = head
    count = 1
    try:
        while count < k:
            count += 1
            cur2 = cur2.next
        while cur2.next is not None:
            cur1 = cur1.next
            cur2 = cur2.next
    except AttributeError:
        print(k, "is out of index")
        return
    return cur1

#   
link = LinkedList()
print("=========before=============")
link.add(1)
link.add(2)
link.add(3)
link.add(4)
link.add(5)
link.add(6)
link.add(7)
link.print_link()
print("=========get_data=============")
print("get_data(link.head, 3):", get_data(link.head, 3).data)
get_data(link.head, 8)
print("===========get_data2=============")
print("get_data2(link.head, 3):", get_data2(link.head, 3).data)
get_data2(link.head, 8)

#   
=========before=============
1
2
3
4
5
6
7
=========get_data=============
get_data(link.head, 3): 5
8 is out of index
===========get_data2=============
get_data2(link.head, 3): 5
8 is out of index