https://oj.leetcode.com/problems/copy-list-with-random-pointer/
http://blog.csdn.net/linhuanmars/article/details/22463599
/**
* Definition for singly-linked list with a random pointer.
* class RandomListNode {
* int label;
* RandomListNode next, random;
* RandomListNode(int x) { this.label = x; }
* };
*/
public class Solution {
public RandomListNode copyRandomList(RandomListNode head)
{
if (head == null)
return null;
Map<RandomListNode, RandomListNode> map = new HashMap<>();
RandomListNode old = head;
RandomListNode precopied = null;
while (old != null)
{
// Copy
RandomListNode copied = new RandomListNode(old.label);
if (precopied != null)
precopied.next = copied;
precopied = copied;
map.put(old, copied);
old = old.next;
}
RandomListNode newhead = map.get(head);
while (head != null)
{
map.get(head).random = map.get(head.random);
head = head.next;
}
return newhead;
}
}