求两个有序单链表的并交集

求并集————————————————————————————

#include <iostream>
#include "./List.h"//利用我们自己实现的单链表List
using namespace std;

void PrintList(List L)
{
     if(NULL == L) return;
     Position pos = First(L);
     cout<<"List L:";
     while(NULL != pos)
     {
          cout<<Retrieve(pos)<<"->";
          pos = pos->next;
     }
     cout<<"NULL"<<endl;;
}
List UnionOfTwoLists(List list1, List list2)
{
     if(NULL == list1  && NULL == list2) return NULL;
     Position p1 = First(list1), p2 = First(list2);
     List out = CreateEmptyList();
     while(NULL != p1 && NULL != p2)
     {
          if(Retrieve(p1) <= Retrieve(p2))
          {
               PushBack(Retrieve(p1), out);
               p1 = p1->next;
          }
          else
          {
               PushBack(Retrieve(p2), out);
               p2 = p2->next;
          }
     }
     if(NULL == p1)
     {
          while(NULL != p2)
          {
               PushBack(Retrieve(p2), out);
               p2 = p2->next;
          }
     }
     else if(NULL == p2)
     {
          while(NULL != p1)
          {
               PushBack(Retrieve(p1), out);
               p1 = p1->next;
          }
     }
     return out;
}
int main(int argc, char const *argv[])
{
     List list1 = CreateEmptyList();
     List list2 = CreateEmptyList();
     for (int i = 0; i < 10; ++i)
          PushBack(i, list1);
     for (int i = 0; i < 20; i += 2)
          PushBack(i, list2);
     PrintList(list1);
     PrintList(list2);
     List res = UnionOfTwoLists(list1, list2);
     PrintList(res);
     return 0;
}

　　

求交集——————————————————————————————

#include <iostream>
#include "./List.h"//利用我们自己实现的单链表List
using namespace std;

void PrintList(List L)
{
     if(NULL == L) cout<<"Error List L is NULL!!!"<<endl;
     Position pos = First(L);
     cout<<"List L:";
     while(NULL != pos)
     {
          cout<<Retrieve(pos)<<"->";
          pos = pos->next;
     }
     cout<<"NULL"<<endl;;
}
List IntersectionOfTwoLists(List list1, List list2)
{
     if(NULL == list1  && NULL == list2) return NULL;
     Position p1 = First(list1);
     List out = CreateEmptyList();
     while(NULL != p1)
     {
          Position tmp = Find(Retrieve(p1), list2);
          if(NULL != tmp)
               PushBack(Retrieve(tmp), out);
          p1 = p1->next;
     }
     return out;
}
int main(int argc, char const *argv[])
{
     List list1 = CreateEmptyList();
     List list2 = CreateEmptyList();
     for (int i = 0; i < 20; ++i)
          PushBack(i, list1);
     for (int i = 0; i < 20; i += 2)
          PushBack(i, list2);
     PrintList(list1);
     PrintList(list2);
     List res = IntersectionOfTwoLists(list1, list2);
     PrintList(res);
     return 0;
}