逆转单链表

非递归实现逆转单链表，遍历单链表时，使用三个指针实现逆转：

public static Node reverseNode(Node node) {
    if (null == node || null == node.next) {
        return node;
    }
    Node pre = null;
    Node cur = node;
    Node next = null;
    while (null != cur) {
        next = cur.next;
        cur.next = pre;
        pre = cur;
        cur = next;
    }
    return pre;
}