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

Supposed the linked list is 1 -> 2 -> 3 -> 4 and you are given the third node with value 3, the linked list should become 1 -> 2 -> 4after calling your function.

这个题的难点是无法得知node前面的node， 那么可以用赋值解决。将要删除的点的值换为下一个点的值，并删除下一个点。 此处需要注意该题有except the tail. 不然需要讨论边界条件。

public void DeleteNode(ListNode node) {        node.val = node.next.val;        node.next = node.next.next;    }

237. Delete Node in a Linked List