单链表逆置

public Node reverseLink(Node head) {
	if (null == head) {
	    return head;
	}
	Node next = null;
	Node pre = null;
	while (head != null) {
	    next = head.next;
	    head.next = pre;
	    pre = head;
	    head = next;
	}
	return pre;
}