两个多项式相加运算

#include <stdio.h>
#include <malloc.h>

typedef struct node
{      float coef;            /*序数*/
       int expn;              /*指数*/
       struct node *next;    /*指向下一个结点的指针*/
} PolyNode;

void InitList(PolyNode *&L)        /*初始化多项式单链表*/
{
    L=(PolyNode *)malloc(sizeof(PolyNode));    /*建立头结点*/
    L->next=NULL;
}

int GetLength(PolyNode *L)        /*求多项式单链表的长度*/
{
    int i=0;
    PolyNode *p=L->next;
    while (p!=NULL)        /*扫描单链表L,用i累计数据结点个数*/
    {
        i++;p=p->next;
    }
    return i;
}

PolyNode *GetElem(PolyNode *L,int i)    /*返回多项式单链表中第i个结点的指针*/
{
    int j=1;
    PolyNode *p=L->next;
    if (i<1 || i>GetLength(L)) 
           return NULL;
    while (j<i)                /*沿next域找第i个结点*/
    {
           p=p->next;j++;
    }
    return p;
}

PolyNode *Locate(PolyNode *L,float c,int e)    /*在多项式单链表中按值查找*/
{
    PolyNode *p=L->next;
    while (p!=NULL && (p->coef!=c ||p->expn!=e))
            p=p->next;
    return p;
}

int InsElem(PolyNode *&L,float c,int e,int i)  /*在多项式单链表中插入一个结点*/
{
    int j=1;
    PolyNode *p=L,*s;
    s=(PolyNode *)malloc(sizeof(PolyNode));
    s->coef=c;s->expn=e;s->next=NULL;
    if (i<1 || i>GetLength(L)+1) 
        return 0;
    while (j<i)        /*查找第i-1个结点*p*/
    {
        p=p->next;j++;
    }
    s->next=p->next;
    p->next=s;
    return 1;
}

int DelElem(PolyNode *L,int i)        /*在多项式单链表中删除一个结点*/
{
    int j=1;
    PolyNode *p=L,*q;
    if (i<1 || i>GetLength(L)) 
        return 0;
    while (j<i)        /*在单链表中查找第i-1个结点*p*/
    {
        p=p->next;j++;
    }
    q=p->next;
    p->next=q->next;
    free(q);
    return 1;
}

void DispList(PolyNode *L)        /*输出多项式单链表的元素值*/
{
    PolyNode *p=L->next;
    while (p!=NULL)
    {
        printf("(%g,%d) ",p->coef,p->expn);
        p=p->next;
    }
    printf("\n");
}
void CreaPolyList(PolyNode *&L,float C[],int E[],int n)
{
    int i;
    InitList(L);
    for (i=0;i<n;i++)
        InsElem(L,C[i],E[i],i+1);
}

void SortPloy(PolyNode *&L)    /*对L的多项式单链表按expn域递增排序*/
{
    PolyNode *p=L->next,*q,*pre;
    L->next=NULL;
    while (p!=NULL) 
    {
        if (L->next==NULL)                     /*处理第1个结点*/
        {
            L->next=p;p=p->next;
            L->next->next=NULL;
           }
        else                                  /*处理其余结点*/
        {
            pre=L;q=pre->next;
            while (q!=NULL && p->expn>q->expn)     /*找q->expn刚大于或等于p->expn的结点*q的前驱结点*pre*/
            {
                pre=q;q=q->next;
            }
            q=p->next;                      /*在*pre结点之后插入*p*/
            p->next=pre->next;
            pre->next=p;
            p=q;
        }    
    }
}

PolyNode *AddPoly(PolyNode *pa,PolyNode *pb)
{
    PolyNode *pc,*p1=pa->next,*p2=pb->next,*p,*tc,*s;
    pc=(PolyNode *)malloc(sizeof(PolyNode));    /*新建头结点*/
    pc->next=NULL;                    /*pc为新建单链表的头结点*/
    tc=pc;                            /*tc始终指向新建单链表的最后结点*/
    while (p1!=NULL && p2!=NULL) 
    {
        if (p1->expn<p2->expn)        /*将*p1结点复制到*s并链到pc尾*/
        {
            s=(PolyNode *)malloc(sizeof(PolyNode));
            s->coef=p1->coef;s->expn=p1->expn;s->next=NULL;
            tc->next=s;tc=s;
            p1=p1->next;
        }
        else if (p1->expn>p2->expn)    /*将*p2结点复制到*s并链到pc尾*/
        {
            s=(PolyNode *)malloc(sizeof(PolyNode));
            s->coef=p2->coef;s->expn=p2->expn;s->next=NULL;
            tc->next=s;tc=s;
            p2=p2->next;
        }
        else   /*p1->expn=p2->expn的情况*/
        {
            if (p1->coef+p2->coef!=0) /*序数相加不为0时新建结点*s并链到pc尾*/
            {
                s=(PolyNode *)malloc(sizeof(PolyNode));
                s->coef=p1->coef+p2->coef;s->expn=p1->expn;
                s->next=NULL;
                tc->next=s;tc=s;
            }
            p1=p1->next;p2=p2->next;
        }
    }
    if (p1!=NULL) p=p1;  /*将尚未扫描完的余下结点复制并链接到pc单链表之后*/
    else p=p2;
    while (p!=NULL) 
    {
        s=(PolyNode *)malloc(sizeof(PolyNode));
        s->coef=p->coef;s->expn=p->expn;s->next=NULL;
        tc->next=s;tc=s;
        p=p->next;
    }
    tc->next=NULL;        /*新建单链表最后结点的next域置空*/
    return pc;
}

void main()
{
    PolyNode *L1,*L2,*L3;
    float C1[]={3,7,5,9},C2[]={-9,8,22};
    int E1[]={1,0,17,8},E2[]={8,1,7};
    InitList(L1);
    InitList(L2);
    InitList(L3);
    CreaPolyList(L1,C1,E1,4);
    CreaPolyList(L2,C2,E2,3);
    printf("两多项式相加运算\n");
    printf("     原多项式A:");DispList(L1);
    printf("     原多项式B:");DispList(L2);
    SortPloy(L1);
    SortPloy(L2);
    printf("排序后的多项式A:");DispList(L1);
    printf("排序后的多项式B:");DispList(L2);
    L3=AddPoly(L1,L2);
    printf("多项式相加结果:");DispList(L3);
}