复杂链表的深度拷贝（给定一个链表，每个节点包涵一个额外增加的随机指针，返回这个链表的深度拷贝）

RNode.h

#pragma once
#include<stdio.h>
#include<stdlib.h>
#include<assert.h>

typedef struct RNode {
   int v;
   RNode* ramdom;
   RNode * next;
}RNode;

RNode.c

#include"RNode"

RNode *Copy(RNode *head){
   if (head = NULL){
       return NULL;
   }
   //分三步走
   RNode* oldNode = head;
//第一步，只复制节点中value和next,让新节点跟在老节点后边
   while (oldNode != NULL){
       RNode* newNode = (RNode*)malloc(sizeof(RNode));
       newNode->v = oldNode->v;

       RNode* oldNext = oldNode->next;
       newNode->next = oldNext;
       oldNode->next= newNode;
       oldNode = oldNext;
   }
//第二步，再处理ramdom的复制
   oldNode = head;
   while (oldNode != NULL){
       RNode * newNode = oldNode->next;
       if (oldNode->ramdom == NULL){
           newNode->ramdom = NULL;
       }
       else{
           newNode->ramdom = oldNode->ramdom->next;
       }
       oldNode = newNode->next;
   }
//第三步，把链表拆成两个
   oldNode = head;
   RNode *newHead = head->next;//把新节点的第一个节点保存一下
   while (oldNode != NULL){
       RNode * newNode = oldNode->next;
       oldNode->next = newNode->next;
       if (newNode->next != NULL){
           newNode->next = newNode->next->next;
       }
       oldNode = oldNode->next;
   }
   return newHead;
}
RNode *BuyNode(int v){
   RNode *node = (RNode*)malloc(sizeof(RNode));
   node->v = v;
   node->next = NULL;
   node->ramdom = NULL;
   return node;
}

main.c

#include"RNode"
int main(){
   RNode *n1 = BuyNode(1);
   RNode *n2 = BuyNode(2);
   RNode *n3 = BuyNode(3);
   RNode *n4 = BuyNode(4);
   n1->next = n2;
   n2->next = n3;
   n3->next = n4;
   n1->ramdom = n3;
   n2->ramdom = n1;
   n3->ramdom = n3;
   n4->ramdom = NULL;
   RNode *rn1 = Copy(n1);
   RNode *rn2 = rn1->next;
   RNode *rn3 = rn2->next;
   RNode *rn4 = rn3->next;
   assert(rn1->v == n1->v);
   assert(rn2->v == n2->v);
   assert(rn3->v == n3->v);
   assert(rn4->v == n4->v);
   assert(rn1->ramdom == rn3);
   assert(rn2->ramdom == rn1);
   assert(rn3->ramdom == rn3);
   assert(rn4->ramdom == NULL);
}