[面试题]给定链表两两倒置？

 

将给定链表两两倒置，如 P1 -> P2 -> P3 -> P4 -> P5,转换为 P2 -> P1 -> P4 -> P3 -> P5.

给定链表类 Node{Node* next},写出该转换函数 Node* Fun(Node* line)

 1  static LinkedListNode Fun(LinkedListNode root)
 2        {
 3            LinkedListNode top = null;
 4            LinkedListNode parent = null;
 5
 6            while (root != null) {
 7                LinkedListNode next = root.Next;
 8                root.Next = null;
 9
10                if (next == null)
11                {
12                    if (parent == null) top = root;
13                    else parent.Next = root;
14                    break;
15                }
16                else
17                {
18                    LinkedListNode nnext = next.Next;
19                    if (parent == null) top = next;
20                    else parent.Next = next;
21                    next.Next = root;
22                    parent = root;
23                    root = nnext;
24                }
25            }
26
27            return top;
28        }