PAT 7-2 终极版

谁能想到我居然在测试点3这里出现了段错误？

//0 1 999 1000这出错了
#include<stdio.h>
#include<stdlib.h>
#include<math.h>
#define OVERFLOW -2 //PAT中没有这个会编译错误
#define OK 1
#define ERROR 0
#define TRUE 1
#define FALSE 0
typedef struct
{
    int coef;
    int expn;
}ElemType;
typedef struct LNode
{
    ElemType data;
    struct LNode *next;
}LNode,*Link,*Position;
typedef struct
{
    Link head,tail;
    int len;
}LinkList;
typedef LinkList Polynomial;
typedef int Status;
Status InitList(LinkList *L)
{
    Link p;
    p=(Link)malloc(sizeof(LNode));
    if(!p) exit(OVERFLOW);
    p->next=NULL;

    (*L).head=(*L).tail=p;
    (*L).len=0;

    return OK;
}
Position GetHead(Polynomial p)
{
    return p.head;
}
Status MakeNode(Link *p,ElemType e)
{
    (*p)=(Link)malloc(sizeof(LNode));
    if(!(*p)) exit(OVERFLOW);
    (*p)->data=e;
    (*p)->next=NULL;
    return OK;
}
void InsFirst(Polynomial *p,Link h,Link s)
{
    s->next=h->next;
    h->next=s;

    if(h==(*p).tail)
        (*p).tail=h->next;

    (*p).len++;
}
int ListLength(LinkList L)
{
    return L.len;
}
ElemType GetCurElem(Link p)
{
    return p->data;
}
Status DelFirst(LinkList *L,Link h,Link *q)
{
    *q=h->next;
    if(*q)
    {
       h->next=(*q)->next;
       if(!h->next)
        (*L).tail=h;

       (*L).len--;
       return OK;
    }
    return ERROR;
}
Position NextPos(LinkList L,Link p)
{
    return p->next;
}
void CreatePolyn(Polynomial *p)
{
    InitList(p);
    Link h=GetHead(*p);
    Link q;
    ElemType e;

    int n;
    scanf("%d",&n);

    int i;
    for(i=1;i<=n;i++)
    {
        scanf("%d%d",&e.coef,&e.expn);
        if(abs(e.expn)<=1000&&abs(e.coef)<=1000) //abs int  fabs double  fabsf float
        {
        MakeNode(&q,e);
        InsFirst(p,h,q);
        h=h->next;
        }
    }
}
void PrintPolyn(Polynomial p)
{
    int n=ListLength(p);
    Link h=GetHead(p);
    Link q=h->next;
    if(n)
    {
        int i;
        for(i=1;i<=n;i++)
        {
            if(i==n) printf("%d %d",q->data.coef,q->data.expn);
            else printf("%d %d ",q->data.coef,q->data.expn);
            q=q->next;
        }
    }
    else printf("%d %d",0,0);
}
int compare(ElemType e1,ElemType e2)
{
    if(e1.expn<e2.expn) return -1;
    else if(e1.expn>e2.expn) return 1;
    else if(e1.expn==e2.expn) return 0;
}
void AddPolyn(Polynomial pa,Polynomial pb,Polynomial *pc)
{
    InitList(pc);

    Link ha,hb,hc,qa,qb;

    ha=GetHead(pa);
    hb=GetHead(pb);
    hc=GetHead(*pc);

    qa=NextPos(pa,ha);
    qb=NextPos(pb,hb);

    ElemType a,b;
    int sum;
    Link s;

    while(qa&&qb)
    {
        a=GetCurElem(qa);
        b=GetCurElem(qb);

        switch(compare(a,b))
        {

        case 1:

           s=(Link)malloc(sizeof(LNode));
           s->next=NULL;
           s->data=qa->data;

           if(s->data.coef==0)
           {
                ha=qa;
                qa=NextPos(pa,ha);
           }
           else
           {
                ha=qa;
                qa=NextPos(pa,ha);
                InsFirst(pc,hc,s);
                hc=NextPos(*pc,hc);
           }

           break;

        case 0:
            sum=qa->data.coef+qb->data.coef;
            if(sum)
            {

                s=(Link)malloc(sizeof(LNode));
                s->next=NULL;

                s->data.coef=sum;
                s->data.expn=qa->data.expn;

                 if(s->data.coef)
                 {
                      InsFirst(pc,hc,s);
                      hc=NextPos(*pc,hc);
                 }

            }

            ha=qa;
            qa=NextPos(pa,ha);

            hb=qb;
            qb=NextPos(pb,hb);

            break;

        case -1:

           s=(Link)malloc(sizeof(LNode));
           s->next=NULL;
           s->data=qb->data;

          if(s->data.coef==0)
          {
               hb=qb;
               qb=NextPos(pb,hb);
          }
           else
           {
                hb=qb;
                qb=NextPos(pb,hb);
                InsFirst(pc,hc,s);
                hc=NextPos(*pc,hc);
           }

           break;

        }
        }

    while(qa)
    {
           s=(Link)malloc(sizeof(LNode));
           s->next=NULL;
           s->data=qa->data;

          if(s->data.coef==0)
          {
               ha=qa;
               qa=NextPos(pa,ha);
          }
          else
          {
               ha=qa;
               qa=NextPos(pa,ha);
               InsFirst(pc,hc,s);
               hc=NextPos(*pc,hc);
          }
    }

    while(qb)
    {
           s=(Link)malloc(sizeof(LNode));
           s->next=NULL;
           s->data=qb->data;

           if(s->data.coef==0)
           {
                hb=qb;
                qb=NextPos(pb,hb);
           }
           else
           {
                hb=qb;
                qb=NextPos(pb,hb);
                InsFirst(pc,hc,s);
                hc=NextPos(*pc,hc);
           }
    }
}
void MultiplyPolyn(Polynomial pa,Polynomial pb,Polynomial *pc)
{
    InitList(pc);

    int a=ListLength(pa);
    int b=ListLength(pb);

    Link ha,hb,hc,qa,qb,qc;

    ha=GetHead(pa);
    hb=GetHead(pb);
    hc=GetHead(*pc);

    qa=NextPos(pa,ha);
    qb=NextPos(pb,hb);

    while(qa&&qb)
    {

    int i;
    Link s;
    for(i=1;i<=b;i++)
    {
        s=(Link)malloc(sizeof(LNode));
        s->next=NULL;

        s->data.coef=qa->data.coef*qb->data.coef;
        s->data.expn=qa->data.expn+qb->data.expn;

        qb=NextPos(pb,qb); //本来在括号内的最下面，由于continue那句移上来了

        if(s->data.coef==0) continue; //对输入的是零项的特殊处理

        InsFirst(pc,hc,s);
        hc=NextPos(*pc,hc);

    }

    a--;
    hc=GetHead(*pc);

    while((a--)>0) //刚开始这里是(a--)，所以导致在输入0和0时出错,因为这种情况是a原本是0，现在是-1，仍可以进入循环，会出现问题
    {
        qa=NextPos(pa,qa);

        qb=NextPos(pb,hb);

        for(i=1;i<=b;i++)
        {
             s=(Link)malloc(sizeof(LNode));
             s->next=NULL;

             s->data.coef=(qa->data.coef)*(qb->data.coef);
             s->data.expn=(qa->data.expn)+(qb->data.expn);

              qb=NextPos(pb,qb); //第一次因为缺少这个地方出错，每次内外qb都需要移动

             if(s->data.coef==0) continue; //一定要确保此指令以下没有必要操作否则就会出错

             qc=hc;
             Link q;

             while(qc->next&&(qc->next->data.expn)>(s->data.expn))
                qc=qc->next;

             if(qc->next&&(qc->next->data.expn==s->data.expn))
             {
                 if((qc->next->data.coef)+(s->data.coef))
                 {
                     qc->next->data.coef+=s->data.coef;
                 }
                 else
                 {
                     DelFirst(pc,qc,&q);
                 }
             }
             else if(qc->next&&(qc->next->data.expn<s->data.expn))
            {
                InsFirst(pc,qc,s);
            }
            else if(!qc->next)
            {
                InsFirst(pc,qc,s);
            }

        }
    }
}
}
int main()
{
    Polynomial Pa,Pb,Pc,Pd;
    CreatePolyn(&Pa);
    CreatePolyn(&Pb);
    AddPolyn(Pa,Pb,&Pc);
    MultiplyPolyn(Pa,Pb,&Pd);
    PrintPolyn(Pd);
    printf("\n");
    PrintPolyn(Pc);
    return 0;
}


测试点0：
4 3 4 -5 2 6 1 -2 0
3 5 20 -7 4 3 1
15 24 -25 22 30 21 -10 20 -21 8 35 6 -33 5 14 4 -15 3 18 2 -6 1
5 20 -4 4 -5 2 9 1 -2 0
Process returned 0 (0x0)   execution time : 29.941 s
Press any key to continue.

测试点1：
2 -1000 1000 1000 0
2 1000 1000 -1000 0
-1000000 2000 2000000 1000 -1000000 0
0 0
Process returned 0 (0x0)   execution time : 30.476 s
Press any key to continue.

测试点2：
3 0 0 0 0 0 0
1 0 0
0 0
0 0
Process returned 0 (0x0)   execution time : 12.448 s
Press any key to continue.

测试点3：
0
1 999 1000
0 0
999 1000
Process returned 0 (0x0)   execution time : 15.822 s
Press any key to continue.