Write a function to delete a node (except the tail) in a singly linked list, given only access to that node.

Given linked list -- head = [4,5,1,9], which looks like following:

    4 -> 5 -> 1 -> 9

Example 1:

Input: head = [4,5,1,9], node = 5
Output: [4,1,9]
Explanation: You are given the second node with value 5, the linked list
             should become 4 -> 1 -> 9 after calling your function.

只给了要删除的Node的reference，所以只能把后面的值向前copy，然后删除最后一个Node

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
    public void deleteNode(ListNode node) {
        if(node == null)
            return;

        ListNode p = node;
        while(p.next != null && p.next.next != null) {
            p.val = p.next.val;
            p = p.next;
        }
        p.val = p.next.val;

        p.next = null;
    }
}