多项式操作的c++实现

#include"define.h"

typedef struct
{
float coef;//系数
int expn;//指数
}term,ElemType;
typedef struct LNode
{
ElemType data;
struct LNode *next;
}*Link;
typedef struct
{
Link head,tail;
int len;
}LinkList;

typedef LinkList polynomial;

status MakeNode(Link &p,ElemType e)
{
//分配由p指向的值为e的节点
p=(Link)malloc(sizeof(LNode));
if(p)
{
p->data.coef=e.coef;
p->data.expn=e.expn;
p->next=NULL;
return OK;
}
else
return 0;
}

Link GetHead(LinkList L)
{
return L.head;
}

status SetCurElem(Link &p,ElemType e)
{
//用e更新p所指节点
if(!p)
{
printf("p is NULL!");
return ERROR;
}
p->data.coef=e.coef;
p->data.expn=e.expn;
return OK;
}

Link LocateElem(LinkList L,ElemType e,status(* compare)(ElemType,ElemType))
{
//返回线性链表中第一个与e满足compare（）判定关系的位置；没有则返回NULL
Link p;
p=L.head->next;
while(p!=NULL&&!(*compare)(p->data,e))
p=p->next;
if(p!=NULL)
return p;
else
return NULL;
}

status InitList(LinkList &L)
{
L.head=L.tail=(Link)malloc(sizeof(LNode));
if(!L.head)
exit(-2);
L.len=0;//长度不算头结点
L.head->next=NULL;
return OK;
}

status ecqual(ElemType a,ElemType b)
{
if(a.expn==b.expn)
return OK;
return ERROR;
}

void InsFirst(Link h,Link s)
{
//插入节点（头插）
s->next=h->next;
h->next=s;
}

void GetCurElem(Link p,ElemType &a)
{
//p所直节点的值赋给a
a.coef=p->data.coef;
a.expn=p->data.expn;
}

Link NextPos(LinkList L,Link p)
{
if(!p->next)
//cout<<"The End!"<<endl;
return NULL;
return p->next;
}

status cmp(ElemType a,ElemType b)
{
if(a.expn>b.expn)
return 1;
else if(a.expn==b.expn)
return 0;
else
return -1;
}

status ListEmpty(LinkList L)
{
//空，返回true
if(L.head->next==NULL)
return true;
else
return false;
}

status DelFirst(Link h,Link &p)
{
//删除表中第一个节点，并以p返回
if(h->next==NULL)
{
cout<<"this is empty!"<<endl;
p=h->next;
return 0;
}
p=h->next;
h->next=p->next;
p->next=NULL;
return OK;
}

void FreeNode(Link &p)
{
free(p);
}

status ClearList(LinkList &L)
{
Link p,h;
h=L.head;
p=h->next;
while(p!=NULL)
{
h=p->next;
FreeNode(p);
p=h;
}

if(!p)
{
L.head->next=NULL;
L.tail=L.head;
L.len=0;
return OK;
}
else
return ERROR;
}

void Append(LinkList &L,Link s)
{
//将s所指的一串节点链接到L的表尾
int i=0;
while(L.tail->next)
{
L.tail=L.tail->next;
}
L.tail->next=s;
while(L.tail->next)
{
L.tail=L.tail->next;
i++;
}
L.len+=i;
}

void DestroyPolyn(polynomial &p)
{
//销毁多项式
if(p.head)
{
FreeNode(p.head);
p.head=p.head->next;
}
}

void PrintPolyn(polynomial p)
{
//打印
Link h;
h=GetHead(p);
h=h->next;
if(h->data.expn==0)
printf("%f",h->data.coef);
printf("%fx^%d",h->data.coef,h->data.expn);
h=h->next;
while(h)
{
if(h->data.expn==0)
printf("%f",h->data.coef);
else
{
if(h->data.coef>0)
printf("+");
printf("%fx^%d",h->data.coef,h->data.expn);
}
h=h->next;
}
printf("/n");
}

int PolynLength(polynomial p)
{
//返回多项式的项数
int i;
i=0;
while(p.head)
{
i++;
p.head=p.head->next;
}
return i;
}

void CreatePolyn(polynomial &p,int m)
{
//输入m项的指数和系数，建立表示一元多项式的有序链表p
Link h,s;
term e;
int i;
InitList(p);
h=GetHead(p);
e.coef=0.0;
e.expn=-1;//设置头结点
SetCurElem(h,e);
//cout<<h->data.coef<<h->data.expn;
cout<<"Please input coef and expn"<<"("<<m<<",Descending)"<<":"<<endl;
for(i=1;i<=m;i++)
{
//cin>>e.coef>>e.expn;
scanf("%f",&e.coef);
scanf("%d",&e.expn);
if(!LocateElem(p,e,ecqual))
if(MakeNode(s,e))
InsFirst(h,s);
}
}

void AddPolyn(polynomial &pa,polynomial &pb,status(* cmp)(ElemType,ElemType))
{
Link ha,hb,qa,qb;
ElemType a,b;
//int T;
float sum;
ha=GetHead(pa);
hb=GetHead(pb);
qa=NextPos(pa,ha);
qb=NextPos(pb,hb);
while(qa&&qb)
{
GetCurElem(qa,a);
GetCurElem(qb,b);
//T=(*cmp)(a,b);
switch((*cmp)(a,b))
{
case -1://多项式pa中当前节点的值较小
ha=qa;
qa=NextPos(pa,qa);
break;
case 0:
sum=a.coef+b.coef;
if(sum!=0)
{
qa->data.coef=sum;//修改系数
ha=qa;
}
else
{
DelFirst(ha,qa);
FreeNode(qa);
}
DelFirst(hb,qb);
FreeNode(qb);
qb=NextPos(pb,hb);
qa=NextPos(pa,ha);
break;
case 1:
DelFirst(hb,qb);
InsFirst(ha,qb);
qb=NextPos(pb,hb);
ha=NextPos(pa,ha);
break;
}
}
if(!ListEmpty(pb))
Append(pa,qb);
FreeNode(hb);
}

void SubtractPolyn(polynomial &pa,polynomial &pb)
{
//多项式相减，并销毁pb
Link ha,hb,qa,qb;
ElemType a,b;
float sub;
ha=GetHead(pa);
hb=GetHead(pb);
qa=NextPos(pa,ha);
qb=NextPos(pb,hb);
while(qa&&qb)
{
GetCurElem(qa,a);
GetCurElem(qb,b);
switch((*cmp)(a,b))
{
case -1:
ha=qa;
qa=NextPos(pa,qa);
break;
case 0:
sub=a.coef-b.coef;
if(sub!=0.0)
{
qa->data.coef=sub;
ha=qa;
}
else
{
DelFirst(ha,qa);
FreeNode(qa);
}
DelFirst(hb,qb);
FreeNode(qb);
qb=NextPos(pb,hb);
qa=NextPos(pa,ha);
break;

case 1:
DelFirst(hb,qb);
qb->data.coef*=-1;
InsFirst(ha,qb);
qb=NextPos(pb,hb);
ha=NextPos(pa,ha);
break;
}
}
if(!ListEmpty(pb))
Append(pa,qb);
FreeNode(hb);
}

/*void contrary(polynomial &q)
{
//逆序
Link p,c,n;
p=NULL;//前一个节点
c=q.head;//当前节点
n=q.head->next;//下一个节点
while(n){//如果没有到链表尾
c->next=p;//逆序当前节点
p=c;//节点前进
c=n;//节点前进
n=n->next;//节点前进
}
c->next=p;
q.head=c;
}*/

void MultiplyPolyn(polynomial &pa,polynomial &pb)
{
//多项式相乘
polynomial sum,T;//sum保存相加结果，T保存每步相乘结果
Link hs,hT,ha,hb,qa,qb,s,t;
term e;
//ElemType a,b;
//int m,n
/*intla,lb;
la=PolynLength(pa);
lb=PolynLength(pb);*/
InitList(sum);
InitList(T);
cout<<1<<endl;
e.coef=0.0;
e.expn=-1;//设置头结点
hT=GetHead(T);
hs=GetHead(sum);
SetCurElem(hs,e);
SetCurElem(hT,e);
ha=GetHead(pa);
if(ha->next==NULL)
cout<<"re"<<endl;
qa=NextPos(pa,ha);
cout<<2<<endl;
hb=GetHead(pb);
while(qa)
{
qb=NextPos(pb,hb);
cout<<3<<endl;
while(qb)
{

e.coef=qa->data.coef*qb->data.coef;
e.expn=qa->data.expn+qb->data.expn;
if(MakeNode(s,e))
{
if(hT->next==NULL)
{
hT->next=s;
t=s;
}
else
{
t->next=s;
s->next=NULL;
t=s;
}
}
qb=qb->next;
}
qa=qa->next;
AddPolyn(sum,T,cmp);
PrintPolyn(sum);
InitList(T);
hT=GetHead(T);
cout<<4<<endl;
}
DestroyPolyn(pb);
hs=GetHead(sum);
hs=NextPos(sum,hs);
ClearList(pa);
Append(pa,hs);
}

void main()
{
polynomial a,b;
CreatePolyn(a,2);
CreatePolyn(b,2);
PrintPolyn(a);
PrintPolyn(b);
//AddPolyn(a,b,cmp);
//MultiplyPolyn(a,b);
SubtractPolyn(a,b);
PrintPolyn(a);
}