复杂链表的复制

题目描述
输入一个复杂链表（每个节点中有节点值，以及两个指针，一个指向下一个节点，另一个特殊指针指向任意一个节点），返回结果为复制后复杂链表的头结点。
思路：
1. 首先根据链表的next遍历一遍，在每个node节点的后面复制一个与node的label相等的节点，如图所示；
2. 再遍历新链表，为复制的节点指定random指针（黄色箭头所示）；
3. 将新链表拆分=原链表+复制后的链表
4. 在操作过程中一定要主要判断节点是否为空
5. 时间复杂度o(n),空间复杂度o(n)

示例代码如下：

/**
 * Copyright (C), 2017
 * FileName: Main
 * Author:   Mengjun Li
 * Date:     2017/10/3 上午11:09
 * Description:
 */

/**
 * @author Mengjun Li
 * @create 2017/10/3
 * @since 1.0.0
 */

public class Main {
    public static void main(String args[]) {
        //定义测试节点
        RandomListNode node1 = new RandomListNode(1);
        RandomListNode node2 = new RandomListNode(2);
        RandomListNode node3 = new RandomListNode(3);
        RandomListNode node4 = new RandomListNode(4);
        RandomListNode node5 = new RandomListNode(5);
        RandomListNode node6 = new RandomListNode(6);
        node1.next = node2;
        node1.random = node3;

        node2.next = node3;
        node2.random = node4;

        node3.next = node4;
        node3.random = node1;

        node4.next = node5;
        node4.random = node2;

        node5.next = node6;
        node5.random = null;

        node6.random = node5;

        System.out.println("原链表的next指针");
        while (head != null) {
            System.out.print(head.label + "-->");
            head = head.next;
        }
        System.out.println("null");

        //Clone链表
        head = Clone(node1);

        System.out.println("clone的链表的next指针");
        while (head != null) {
            System.out.print(head.label + "-->");
            head = head.next;
        }
        System.out.println("null");

        System.out.println("原链表的random指针");
        head = node1;
        while (head != null) {
            if (head.random != null)
                System.out.print(head.label + "-->"+head.random.label+"， ");
            else
                System.out.print(head.label + "--> null, ");
            head = head.next;
        }
        System.out.println("");

        head = Clone(node1);
        System.out.println("clone的链表的random指针");
        while (head != null) {
            if (head.random != null)
                System.out.print(head.label + "-->"+head.random.label+"， ");
            else
                System.out.print(head.label + "--> null, ");
            head = head.next;
        }

    }

    public static RandomListNode Clone(RandomListNode pHead) {
        if (pHead == null)
            return pHead;
        RandomListNode tmp = null, oHead = pHead, newNode;
        //第一步：在原链表中每一个节点的后面复制前面一个节点
        while (oHead != null) {
            newNode = new RandomListNode(oHead.label);
            tmp = oHead.next;
            oHead.next = newNode;
            newNode.next = tmp;
            oHead = tmp;
        }
        oHead = pHead;
        //第二步：给复制的节点的random指针赋值
        while (oHead != null) {
            if (oHead.random != null)//random可能为null
                oHead.next.random = oHead.random.next;
            else
                oHead.next.random = null;
            oHead = oHead.next.next;
        }
        //将复制后的链表和原链表断开
        oHead = pHead;
        newNode = pHead.next;
        while (oHead != null) {
            tmp = oHead.next;
            if (tmp != null)
                oHead.next = tmp.next;
            oHead = tmp;
        }
        return newNode;
    }

}

class RandomListNode {
    int label;
    RandomListNode next = null;
    RandomListNode random = null;

    RandomListNode(int label) {
        this.label = label;
    }
}

输出如下：

原链表的next指针
1-->2-->3-->4-->5-->6-->null
clone的链表的next指针
1-->2-->3-->4-->5-->6-->null
原链表的random指针
1-->3， 2-->4， 3-->1， 4-->2， 5--> null, 6-->5， 
clone的链表的random指针
1-->3， 2-->4， 3-->1， 4-->2， 5--> null, 6-->5，