两个集合取并集

集合La Lb 链表实现 得到 La U Lb

#include <stdio.h>
#include <stdlib.h>

#define LEN sizeof(struct student)
#define FORMANT() \
                  printf("==================================\n");\
                  printf("num     eng     math     avg(auto)\n");\
                  printf("==================================\n")

struct student
{
       int    num;
       float  english;
       float  math;
       float  avg;
       struct student *next;
};

int n= 0;

struct student *creat();
void prt(struct student *head);
struct student *add(struct student *head_La, struct student *head_Lb);
struct student *compare(struct student *head_La, struct student *p_Lb);

int main(int argc, char *argv[])
{
  struct student *head_La, *head_Lb, *head_Lc;
  int pos,position;
 
  printf("创建链表La：\n");
  head_La = creat();
  prt(head_La);
  n = 0;
 
  printf("\n创建链表Lb：\n");
  head_Lb = creat();
  prt(head_Lb);
  n = 0;
 
  printf("\n生成链表Lc = La U Lb ：");
  head_Lc = add(head_La, head_Lb);
  prt(head_Lc);
 
  system("PAUSE");   
  return 0;
}

struct student *creat()
{
       struct student *p1, *p2, *head = NULL;
      
       p1 = p2 = (struct student *)malloc(LEN);
       printf("请输入学生的信息：\n");
       FORMANT();
       scanf("%d%f%f", &p1->num,&p1->english,&p1->math);
       p1->avg = (p1->english + p1->math)/2;
      
       while(p1->num != 0)
       {
               n++;
               if(n == 1)
               {
                    head = p1;
               }     
               else
               {
                   p2->next = p1;
               }
               p2 = p1;
               p1 = (struct student *)malloc(LEN);
               scanf("%d%f%f", &p1->num,&p1->english,&p1->math);
               p1->avg = (p1->english + p1->math)/2;
       }   
       p1->next = NULL;
       return head;
}

void prt(struct student *head)
{
     struct student *p1;
     p1 = head;
     printf("\n显示链表:\nnow there are %d datas.\n",n);
     FORMANT();
     while(p1 != NULL)
     {
           printf("%-8d%-8.2f%-9.2f%-8.2f\n", p1->num, p1->english, p1->math, p1->avg);
           p1=p1->next;
     }
}

struct student *add(struct student *head_La, struct student *head_Lb)
{
       struct student *head_Lc, *p_La, *p_Lb, *p_Lb1, *p_Lc, *p_Lc1;
       p_La = head_La;
       p_Lb = head_Lb;
       p_Lc = p_Lc1 = (struct student *)malloc(LEN);
       head_Lc = p_Lc;
      
       while(p_La != NULL)
       {    
             p_Lc->num = p_La->num;
             p_Lc->english = p_La->english;
             p_Lc->math = p_La->math;
             p_Lc->avg = p_La->avg;
             p_La = p_La->next;
             p_Lc1->next = p_Lc;
             p_Lc1 = p_Lc;
             p_Lc = (struct student *)malloc(LEN);
             n++;
       }
       while(p_Lb != NULL)
       {
             p_Lb1 = compare(head_La, p_Lb);    
             if(p_Lb1 != NULL)
             {
                      p_Lc->num = p_Lb1->num;
                      p_Lc->english = p_Lb1->english;
                      p_Lc->math = p_Lb1->math;
                      p_Lc->avg = p_Lb1->avg;
                      p_Lc1->next = p_Lc;
                      p_Lc1 = p_Lc;
                      p_Lc = (struct student *)malloc(LEN);
                      n++;   
             }
             p_Lb = p_Lb->next;
       }
       return head_Lc;
}

struct student *compare(struct student *head_La, struct student *p_Lb)
{
       struct student *p_La = head_La;
       int flag = 0;

       while(p_La != NULL)
       {
            if(p_La->num != p_Lb->num)
                  flag = 1;
            else
                  flag = 0;
            p_La = p_La->next;
       }
       if(flag)
                return p_Lb;
       else   
                return NULL;
}