206. reverse linked list

public static ListNode reverseList(ListNode head) {
	if(head.next == null || head == null){
		return head;
	}else{
		ListNode node = reverseList(head.next);
		//这里反转使用head，而不是node，
		//node 只是用来返回
		//置反
		head.next.next = head;
		//去掉原来的指针
		head.next = null;
		return node;
	}
}