链表中倒数第k个节点

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

def solve():
    def getKthFromEnd(head, k):
        fast = slow = head
        for _ in range(k):
            fast = fast.next
        while fast:
            fast = fast.next
            slow = slow.next
        return slow
    head = ListNode(1, ListNode(2, ListNode(3, ListNode(4, ListNode(5)))))
    result = getKthFromEnd(head, 2)
    print(result.val)