题解 | #链表中倒数最后k个结点#

# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None
#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param pHead ListNode类 
# @param k int整型 
# @return ListNode类
#
class Solution:
    def FindKthToTail(self , pHead: ListNode, k: int) -> ListNode:
        # write code here
        ans = ListNode(0)
        if pHead==None:
            if k>0:
                return ans.next
            else:
                return pHead
        p = pHead
        L = 0
        while p:
            p = p.next
            L = L + 1
        p = pHead
        if L > k:
            for i in range(L-k):
                ans = p
                p = p.next
            return p
        elif L == k:
            return pHead
        else:
            return ans.next