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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.

    参考:深度拷贝,浅度拷贝,Lazy拷贝解析http://www.2cto.com/kf/201401/276086.html

    思路: Step 1: 首先指向在原链表的每个节点后面,复制一个新的节点,原链表长度变为 2 倍

    random 指针指向的是 原链表节点 random 指针指向的节点的后面的那个节点

    Step 2: 将链表拆成两个 lists

    C++实现代码:

    #include<iostream>
    #include<new>
    using namespace std;
    
    
    // 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)
        {
            if(head==NULL)
                return NULL;
            RandomListNode *p=head;
            while(p)
            {
                RandomListNode *q=new RandomListNode(p->label);
                q->next=p->next;
                p->next=q;
                p=q->next;
            }
            p=head;
            while(p)
            {
                if(p->random)
                    p->next->random=p->random->next;
                p=p->next->next;
            }
            RandomListNode *retHead = NULL;
            RandomListNode *tRet = NULL;
            p = head;
            while(p)
            {
                if(retHead == NULL)
                {
                    retHead = p->next;
                    tRet = retHead;
                    p->next = p->next->next;
                    p = p->next;
                }
                else
                {
                    tRet->next = p->next;
                    p->next = p->next->next;
                    p = p->next;
                    tRet = tRet->next;
                }
            }
            return retHead;
        }
        void createList(RandomListNode *&head)
        {
            RandomListNode *p=NULL;
            int i=0;
            int arr[10]= {10,9,8,7,6,5,4,3,2,1};
            for(i=0; i<10; i++)
            {
                if(head==NULL)
                {
                    head=new RandomListNode(arr[i]);
                    if(head==NULL)
                        return;
                }
                else
                {
                    p=new RandomListNode(arr[i]);
                    p->next=head;
                    head=p;
                }
            }
        }
    };
    
    int main()
    {
        Solution s;
        RandomListNode *L=NULL;
        s.createList(L);
        RandomListNode *L2=s.copyRandomList(L);
        RandomListNode *p=L2;
        while(p)
        {
            cout<<p->label<<" ";
            p=p->next;
        }
    }
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  • 原文地址:https://www.cnblogs.com/wuchanming/p/4122448.html
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