LeetCode OJ--Copy List with Random Pointer **

https://oj.leetcode.com/problems/copy-list-with-random-pointer/

灵活的指针链表应用。

每个节点有两个指针next,random，对本链表做一个深拷贝。就是完全用新内存弄出一个一样的来。

a链表：  a b c三个node

b链表： a1 b1 c1三个node

a->next = a1

a1->next = b

这样建立关系,之后再扫一遍，对a1的random赋值，之后再扫一遍，对a1->next赋值。

#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
using namespace std;

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;
        for(RandomListNode *pointer = head;pointer!=nullptr;)
        {
            RandomListNode *link2node = new RandomListNode(pointer->label);
            link2node->next = pointer->next;
            pointer->next = link2node;

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

        RandomListNode *head2 = head->next;
        RandomListNode * pointer2 = nullptr;
        for(RandomListNode *pointer = head;pointer!=nullptr;pointer = pointer->next)
        {
            pointer2 = pointer->next->next;
            if(pointer2 != nullptr)
            {
                pointer->next->next = pointer->next->next->next;
                pointer->next = pointer2;
            }
            else
            {
                pointer->next->next = NULL;
                pointer->next = NULL;
            }
        }
        return head2;
    }
};
int main()
{
    RandomListNode *n1 = new RandomListNode(1);
    RandomListNode *n2 = new RandomListNode(2);
    RandomListNode *n3 = new RandomListNode(3);
    RandomListNode *n4 = new RandomListNode(4);
    n1->next = n2;
    n2->next = n3;
    n3->next = n4;
    n1->random = n2;     
    n2->random = n1;
    n4->random = n4;
    class Solution mys;
    mys.copyRandomList(n1);
}