#include?
#include?

typedef?struct?node{//定義節(jié)點(diǎn)類型?
float?coef;?
int?expn;?
struct?node?*?next;?
}PLOY;?

void?start（）//用戶選擇界面?
{?
printf（“************************************\n“）;?
printf（“?兩個(gè)一元多項(xiàng)式的相加/相減，相乘:\n“）;?
printf（“************************************\n“）;?
printf（“請(qǐng)選擇操作:\n“）;?
printf（“0.退出\n“）;?
printf（“1.兩個(gè)一元多項(xiàng)式相加\n“）;?
printf（“2.兩個(gè)一元多項(xiàng)式相乘\n“）;?
printf（“3.兩個(gè)一元多項(xiàng)式相減\n“）;??
}?
void?insert（PLOY?*headPLOY?*inpt）//查找位置插入新鏈節(jié)程序?
{?
PLOY?*pre*now;?
int?signal=0;?
pre=head;//pre定義為現(xiàn)在的前一個(gè)鏈節(jié)?
if（pre->next==NULL）?{pre->next=inpt;}?
else?{now=pre->next;?
while（signal==0）?
{?
if（inpt->expnexpn）//當(dāng)新鏈節(jié)小于現(xiàn)在的連接時(shí)向后移一個(gè)鏈節(jié)?
{?
if（now->next==NULL）?
{?
now->next=inpt;?
signal=1;?
}?
else?
{?
pre=now;?
now=pre->next;?
}?
}?
else?
if（inpt->expn>now->expn）//如果發(fā)現(xiàn)比現(xiàn)在的鏈節(jié)大了就插入到這個(gè)連接的前面?
{?
inpt->next=now;?
pre->next=inpt;?
signal=1;?
}?
else?
{?
now->coef=now->coef+inpt->coef;?
signal=1;?
free（inpt）;//與當(dāng)前鏈節(jié)相等指數(shù)?
if（now->coef==0）?
{?
pre->next=now->next;?
free（now）;?
}?
}?
}?
}?
}?

PLOY?*creat（char?ch）//輸入多項(xiàng)式?
{?
PLOY?*head*inpt;?
float?x;?
int?y;?
head=（PLOY?*）malloc（sizeof（PLOY））;//創(chuàng)建鏈表頭?
head->next=NULL;?
printf（“請(qǐng)輸入一元多項(xiàng)式%c:（格式是：系數(shù)?指數(shù)；以0?0?結(jié)束！）\n“ch）;?
scanf（“%f?%d“&x&y）;?
while（x!=0）?
{?
inpt=（PLOY?*）malloc（sizeof（PLOY））;//創(chuàng)建新鏈節(jié)?
inpt->coef=x;?
inpt->expn=y;?
inpt->next=NULL;?
insert（headinpt）;//不然就查找位置并且插入新鏈節(jié)?
printf（“請(qǐng)輸入一元多項(xiàng)式%c的下一項(xiàng):（以0?0?結(jié)束！）\n“ch）;?
scanf（“%f?%d“&x&y）;?
}?
return?head;?
}?

PLOY?*addPLOY（PLOY?*headPLOY?*pre）//多項(xiàng)式相加?
{?
PLOY?*inpt;?
int?flag=0;?
while（flag==0）?
{?
if（pre->next==NULL）?
flag=1;//當(dāng)現(xiàn)在指向空時(shí)跳出循環(huán)?
else?
{?
pre=pre->next;?
inpt=（PLOY?*）malloc（sizeof（PLOY））;//創(chuàng)建新鏈節(jié)?
inpt->coef=pre->coef;?
inpt->expn=pre->expn;?
inpt->next=NULL;?
insert（headinpt）;?
}//否則把當(dāng)前“g（x）”的鏈節(jié)插入到“y（x）”中?
}?
return?head;?
}?

PLOY?*minusPLOY（PLOY?*headPLOY?*pre）//多項(xiàng)式相加?
{?
PLOY?*inpt;?
int?flag=0;?
while（flag==0）?
{?
if（pre->next==NULL）?
flag=1;//當(dāng)現(xiàn)在指向空時(shí)跳出循環(huán)?
else?
{?
pre=pre->next;?
inpt=（PLOY?*）malloc（sizeof（PLOY））;//創(chuàng)建新鏈節(jié)?
inpt->coef=0-pre->coef;?
inpt->expn=pre->expn;?
inpt->next=NULL;?
insert（headinpt）;?
}//否則把當(dāng)前“g（x）”的鏈節(jié)插入到“y（x）”中?
}?
return?head;?
}?

PLOY?*byPLOY（PLOY?*head1PLOY?*head2）