copy-list-with-random-pointer

题目：

A linked list is given such that each node contains an additional random pointer which could point to any node in the list or null.

Return a deep copy of the list.

/**
* Definition for singly-linked list with a random pointer.
* struct RandomListNode {
*     int label;
*     RandomListNode *next, *random;
*     RandomListNode(int x) : label(x), next(NULL), random(NULL) {}
* };
*/
class Solution
{
public:
RandomListNode *copyRandomList(RandomListNode *head)
{

for (RandomListNode* cur = head; cur != NULL;)
{
RandomListNode* node = new  RandomListNode(cur->label);

node->next = cur->next;
cur->next = node;
cur = node-> next;

}

for (RandomListNode* cur = head; cur != NULL;)
{
if (cur->random != NULL)
{
cur->next->random = cur->random->next;
}
cur = cur->next->next;
}

// 拆链表
RandomListNode dummy(-1);
for (RandomListNode* cur = head, *new_cur = &dummy; cur != NULL;)
{
new_cur->next = cur->next;
new_cur = new_cur->next;
cur->next = cur->next->next;
cur = cur->next;
}

return dummy.next;
}
};