Reverse A Linked List

在stackoverflow上看到一个好的方案。http://stackoverflow.com/questions/354875/reversing-a-linked-list-in-java-recursively

Three questions to ask:

1. What is the reverse of null (the empty list)? null.
2. What is the reverse of a one element list? the element.
3. What is the reverse of an n element list? the reverse of the second element on followed by the first element.

public ListNode Reverse(ListNode list)
{
    if (list == null) return null; // first question

    if (list.next == null) return list; // second question

    // third question - in Lisp this is easy, but we don't have cons
    // so we grab the second element (which will be the last after we reverse it)

    ListNode secondElem = list.next;

    // bug fix - need to unlink list from the rest or you will get a cycle
    list.next = null;

    // then we reverse everything from the second element on
    ListNode reverseRest = Reverse(secondElem);

    // then we join the two lists
    secondElem.Next = list;

    return reverseRest;
}

另一篇好东西在这里http://blog.youkuaiyun.com/feliciafay/article/details/6841115