leetCode160|链表中倒数第k个节点

示例：

给定一个链表: 1->2->3->4->5, 和 k = 2.

返回链表 4->5.

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;

public class GetKthFromEndTest {
    public static void main(String[] args) {
        ListNode l1 = new ListNode(1);
        ListNode l2 = new ListNode(2);
        ListNode l3 = new ListNode(3);
        ListNode l4 = new ListNode(4);
        ListNode l5 = new ListNode(5);
        l1.next = l2;
        l2.next = l3;
        l3.next = l4;
        l4.next = l5;
        int k = 2;
        ListNode listNode = getKthFromEnd(l1, k);
        System.out.println("listNode = " + listNode);


    }

    public static ListNode getKthFromEnd(ListNode head, int k) {
        if (head == null || head.next == null) {
            return head;
        }
        ListNode slow = head;
        ListNode fast = head;
        for (int i = 0; i < k; i++) {
            fast = fast.next;
        }
        while (fast != null) {
            slow = slow.next;
            fast = fast.next;
        }
        return slow;
    }


}