题解 | #链表中倒数第k个结点#

import java.util.*;
/*
public class ListNode {
    int val;
    ListNode next = null;

    ListNode(int val) {
        this.val = val;
    }
}*/
public class Solution {
    public ListNode FindKthToTail(ListNode head, int k) {
        if (k <= 0) {
            return null;
        }
        if (head == null) {
            return null;
        }
        ListNode fast = head;
        ListNode slow = head;
        int count = 0;
        while (count != k - 1) {
            if (fast.next != null) {
                fast = fast.next;
                count++;
            } else {
                return null;
            }
        }
        while (fast.next != null) {
            fast = fast.next;
            slow = slow.next;
        }
        return slow;
    }
}