剑指offer 14：链表中倒数第k个节点

/*
public class ListNode {
    int val;
    ListNode next = null;

    ListNode(int val) {
        this.val = val;
    }
}*/
public class Solution {
    public ListNode FindKthToTail(ListNode head, int k) {
        ListNode p1 = head, p2 = head;
        while(p1 != null && k-- >0){
            p1 = p1.next;
        }
        if(k > 0) return null;
        while(p1 != null){
            p1 = p1.next;
            p2 = p2.next;
        }
        return p2;
    } 
}