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 Copy List with Random Pointer

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.

算法分为三步：

1. copy and insert

2. set random pointer of copied node

3. split these two list

class Solution {
public:
    RandomListNode *copyRandomList(RandomListNode *head) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        if(head == NULL) return NULL;
        //1. copy and insert
        RandomListNode* pCurNode = head;
        while(pCurNode != NULL)
        {
            //copy
            RandomListNode* tmp = new RandomListNode(pCurNode->label);
            //insert
            RandomListNode* pNextNode = pCurNode->next;
            pCurNode->next = tmp;
            tmp->next = pNextNode;
            pCurNode = pNextNode;
        }
        //2. set random pointer of copied node
        pCurNode = head;
        while(pCurNode != NULL)
        {
            if(pCurNode->random != NULL)
                pCurNode->next->random = pCurNode->random->next;
            else
                pCurNode->next->random = NULL;
            pCurNode = pCurNode->next->next;
        }
        //3. split these two list
        RandomListNode* newHead = head->next;
        pCurNode = head;
        while(pCurNode != NULL)
        {
            RandomListNode* pCopiedNode = pCurNode->next;
            pCurNode->next = pCurNode->next->next;
            if(pCurNode->next != NULL)
                pCopiedNode->next = pCurNode->next->next;
            else
                pCopiedNode->next = NULL;
            pCurNode = pCurNode->next;
        }

        return newHead;
    }
};