剑指Offer 22 链表中倒数第k个节点

链表中倒数第k个节点

输入一个链表，输出该链表中倒数第k个结点。

# -*- coding:utf-8 -*-
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution:
    def FindKthToTail(self, head, k):
        fast = ListNode(0)
        slow = ListNode(0)
        if head == None:
            return None
        safehead = ListNode(head.val)
        safehead.next = head.next
        fast = head
        count = 0
        while count != k:
            if fast == None:
                return None
            fast = fast.next
            count += 1
        slow = safehead
        while fast != None:
            fast = fast.next
            slow = slow.next
        return slow

 

Java版本代码：

class Solution {
    public ListNode getKthFromEnd(ListNode head, int k) {
        if (head == null) {
            return null;
        }

        ListNode safeHead = new ListNode(head.val);
        safeHead.next = head.next;
        ListNode fast = head;
        int count = 0;
        while (count != k) {
            if (fast == null) {
                return null;
            }
            fast = fast.next;
            count++;
        }
        ListNode slow = safeHead;
        while (fast != null) {
            fast = fast.next;
            slow = slow.next;
        }
        return slow;
    }
}