leetcode_138_ Copy List with Random Pointer

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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;    }};

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