[讨论]一元多项式计算

#include<stdio.h>
#include<stdlib.h>

typedef struct node
{ int coef;

int exp;

struct node *next;

}Node;

int string_change_num(char *start,int *end);

Node *string_change_link(int *end,int n);

Node *order(Node *head);

Node *unite(Node *head);

void print (Node *head);

void main()
{ Node *head,*head1;

char str[255];

int i,end[255],n;

printf("输入字符,以'='号结束:\n\n");

printf("例如要输入 3x^3+4x^3,就要输入3x3+4x3\n\n");
for(i=0;i<255;i++)
{
scanf("%c",&str[i]);

if(str[i]=='=')

break;
}

str[i]='\0';

n=string_change_num(str,end);

head=string_change_link(end,n);

head1=order(head);

printf("按照指数从小到大排序的多项式:\n\n");

print(head1);

printf("\n");

printf("合并后的多项式是:\n");

head1=unite(head);

head=order(head1);

print(head);

printf("\n");
}

int string_change_num(char *start,int *end)
{ int i=0,j=0,k,sum=0,c=0,flag=1;

while(start[i]!='\0')
{
if(start[i]=='x'||start[i]=='+'||start[i]=='-')
{
if(start[i]=='x'&&start[j-1]=='-')

flag=0;

if(start[i]=='x'&&start[j-1]=='+')

flag=1;

for(k=j;k<i;k++)

sum=sum*10+start[k]-'0';

if(flag==0)
{
sum=-sum;

flag=1;
}

end[c++]=sum;

sum=0;

j=i+1;
}
i++;
}
while(start[j]>'0'&&start[j]<'9')
{ sum=sum*10+start[j]-'0';

j++;
}

end[c++]=sum;

return c;

}

Node *string_change_link(int *end,int n)
{ Node *head,*p,*s;

int i=0;

head=(Node *)malloc(sizeof(Node));

head->next=NULL;

p=head;

while(i<n)
{
s=(Node *)malloc(sizeof(Node));

if(i%2==0)

s->coef=end[i];

i++;

if(i%2!=0)

s->exp=end[i];

p->next=s;

p=s;

i++;
}

p->next=NULL;

return head;
}

Node *order(Node *head)
{ Node *p,*q,*t,*s,*h;
h=(Node *)malloc(sizeof(Node));
h->next=head;
p=h;
while(p->next->next!=NULL)
{
for(s=p,q=p->next;q->next!=NULL;q=q->next)

if(q->next->exp<s->next->exp)

s=q;
if(s!=q)
{
t=s->next;

s->next=t->next;

t->next=p->next;

p->next=t;
}
p=p->next;
}
head=h->next;

free(h);

return head;
}

Node *unite(Node *head)
{ Node *p,*q,*q1,*p1;

q1=head;

p1=head;

p=head->next;

q=p->next;

while(p->next!=NULL)
{
for(q=p->next;q!=NULL;q=q->next)
{
if(p->exp==q->exp)
{
while(q1->next!=q)

q1=q1->next;

while(p1->next!=p)

p1=p1->next;

if(p->coef+q->coef==0)
{
if(q==p->next)
{
p1->next=q->next;

free(q);

free(p);

q=p1;

p=p1;

}
else{
p1->next=p->next;

free(p);

p=p1;

q1->next=q->next;

free(q);

q=q1;
}
p1=head;

q1=head;
}
else{
p->coef=p->coef+q->coef;

q1->next=q->next;

free(q);

q=q1;

p1=head;

q1=head;
}
}
}
if(p->next!=NULL)

p=p->next;
if(p->next==NULL)

break;
}
return head;
}

void print(Node *head)
{ Node *p;

p=head->next;

if(p==NULL)

printf("0");

else
{
if(p->exp==0)

printf("%d",p->coef);

else
if(p->exp==1)

printf("%dx",p->coef);

else

if(p->coef==1)

printf("x^%d",p->exp);

else if(p->coef==-1)

printf("-x^%d",p->exp);

else

printf("%dx^%d",p->coef,p->exp);
p=p->next;

while(p!=NULL)
{
if(p->exp==0)

printf("%d",p->coef);

else
if(p->exp==1)
{
if(p->coef>0)

printf("+%dx",p->coef);

else printf("%d",p->coef);
}

else if(p->coef>0&&p->coef!=1&&p->exp!=-1)

printf("+%dx^%d",p->coef,p->exp);

else if(p->coef<0&&p->coef!=1&&p->exp!=-1)

printf("%dx^%d",p->coef,p->exp);

else if(p->coef==1)

printf("+x^%d",p->exp);

else if(p->coef==-1)

printf("-x^%d",p->exp);

p=p->next;
}

}
}

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