12121.cpp

多项式的加减乘法的链表实现的程序在C++中

#include<iostream.h> 

class term 
{public: 
term(int c,int e); 
term(int c,int e,term* nxt); 
term*insertafter(int c,int e); 
private: 
int coef;//系数 
int exp; //指数
term*link; 
friend ostream & operator<<(ostream&,const term &); 
friend class polynominal; 
}; 
term::term(int c,int e):coef(c),exp(e) 
{link=0; 
} 
term::term(int c,int e,term*nxt):coef(c),exp(e) 
{link=nxt; 
} 
term*term::insertafter(int c,int e) 
{link=new term(c,e,link); 
return link; 
} 
ostream &operator<<(ostream & out,const term & val) 
{if(val.coef==0) return out; 
else if(val.coef==1&&val.exp!=0) out<<""; //如果系数为1，就不显示系数 
else 
out<<val.coef; 
switch(val.exp){ 
case 0:break; 
case 1:out<<"X";break; 
default:out<<"X^"<<val.exp;break; 
} 
return out; 
} 

class polynominal 
{public: 
polynominal(); 
~polynominal(); 
void addterms(istream& in); 
void output(ostream& out)const; 
void polyadd(polynominal& r); 
void polysub(polynominal& r); 
void polymul(polynominal& r); 
private: 
term* thelist; 
friend ostream & operator <<(ostream &,const polynominal &); 
friend istream & operator >>(istream&,polynominal &); 
friend polynominal &operator +(polynominal &,polynominal &); 
friend polynominal &operator -(polynominal &,polynominal &); 
friend polynominal &operator *(polynominal &,polynominal &); 
}; 

polynominal::polynominal() 
{thelist=new term(0,-1); 
thelist->link=thelist; 
} 

polynominal::~polynominal() 
{term* p=thelist->link; 
while(p!=thelist){ 
thelist->link=p->link; 
delete p; 
p=thelist->link; 
} 
delete thelist; 
} 


void polynominal::addterms(istream & in) 
{term* q=thelist; 
int c,e; 
for(;;){ 
cout<<"请输入一个多项式(coef,exp):\n"<<endl; 
cin>>c>>e; 
if(e<0)break; 
q=q->insertafter(c,e); 
} 
} 

void polynominal::output(ostream & out)const 
{int first=1;term * p=thelist->link; 
cout<<"输出多项式为:\n"<<endl; 
for(;p!=thelist;p=p->link){ 
if(!first && (p->coef>0))out<<"+"; 
first=0; 
out<<*p; 
} 
cout<<"\n"<<endl; 
} 

void polynominal::polyadd(polynominal&r)//加法 
{term* q,*q1=thelist,*p; 
p=r.thelist->link; 
q=q1->link; 
while(p->exp>=0) 
{ 
while(p->exp<q->exp) 
{ 
q1=q;q=q->link; 
} 
if(p->exp==q->exp) 
{q->coef=q->coef+p->coef; 
p=p->link; 
if(q->coef==0) 
{ 
q1->link=q->link;delete(q); 
q=q1->link; 
} 
else 
{ 
q1=q;q=q->link; 
} 
} 
else 

{ q1=q1->insertafter(p->coef,p->exp); 
p=p->link; 
} 
} 
} 
void polynominal::polysub(polynominal & r) //减法 
{term* q,*q1=thelist,*p; 
p=r.thelist->link; 
q=q1->link; 
while(p->exp<q->exp) 
{ 
q1=q;q=q->link; 
} 
if(p->exp==q->exp) 
{ 
q->coef=q->coef-(p->coef); 
p=p->link; /////////////////////////////// 
if(q->coef==0) 
{ 
q1->link=q->link;delete(q); 
q=q1->link; 
} 
else 
{ 
q1=q;q=q->link; 
} 
} 
else 
{p->coef=0-(p->coef); /////////////////////////////////// 
q1=q1->insertafter(p->coef,p->exp); 
p=p->link; 
} 
} 
 
ostream& operator<<(ostream & out,const polynominal &x) 
{x.output(out);return out; 
} 
istream& operator >>(istream& in,polynominal &x) 
{x.addterms(in);return in; 
} 

polynominal&operator +(polynominal &a,polynominal &b) 
{a.polyadd(b);return a; 
} 
polynominal&operator -(polynominal &a,polynominal &b) 
{a.polysub(b);return a; 
} 
void main() 
{polynominal p,q; 
int i,n=0,m=0; 
cin>>q;cout<<q; 
cin>>p;cout<<p; 
th:cout<<"请选择要进行的操作："<<endl<<"1。运行q+p"<<endl<<"2。运行q-p"<<endl<<"3。运行q*p"<<endl<<"其他：退出"<<endl; 
cin>>i; 
switch(i){ 
case 1:if(m){q=q+p+p;m=0;cout<<q;goto th;} 
else {q=q+p;cout<<q;n=1;goto th;} 
case 2:if(n) 
{q=q-p-p;cout<<q;n=0;goto th;} 
else {q=q-p;cout<<q;m=1;goto th;} 
case 3:cout<<"Byebye~"<<endl; 
} 
}