Polynomial Addition and Multiplication using Linked List

Polynomial Addition and Multiplication using Linked List

#include<stdio.h>
#include<stdlib.h>
struct node
{
 int coef;
 int exp;
 struct node *link;
};
void insert_term(struct node **,int,int);
void traverse(struct node *);
void poly_add(struct node **,struct node **,struct node **);
void poly_pdt(struct node **,struct node **,struct node **);
void main()
{
 struct node *start_p=NULL,*start_q=NULL,*start_r=NULL;
 int i,n,c,e;
 printf("Enter first polynomial?\n");
 printf("Enter no of terms?\n");
 scanf("%d",&n);
 for(i=0;i<n;i++)
 {
  printf("Enter %d term\n",i+1);
  printf("Enter coefficient\n");
  scanf("%d",&c);
  printf("Enter exponent\n");
  scanf("%d",&e);
  insert_term(&start_p,c,e);
 }
 printf("Enter second polynomial\n");
 printf("Enter no of terms?\n");
 scanf("%d",&n);
 for(i=0;i<n;i++)
 {
  printf("Enter %d term",i+1);
  printf("Enter coefficient\n");
  scanf("%d",&c);
  printf("Enter exponent\n");
  scanf("%d",&e);
  insert_term(&start_q,c,e);
 }
 printf("First polynomial:\n");
 traverse(start_p);
 printf("second polynomial:\n");
 traverse(start_q);
 poly_add(&start_p,&start_q,&start_r);
 printf("sum of two polynomial:\n");
 traverse(start_r);
 start_r=NULL;
 poly_pdt(&start_p,&start_q,&start_r);
 printf("Product of the two polynomial:\n");
 traverse(start_r);
 
}
void insert_term(struct node **start,int c,int e)
{ 
 struct node *temp,*temp1,*prev;
 if (*start==NULL)
 {
  temp=(struct node*)malloc(sizeof(struct node));
  if (temp==NULL)
   printf("Node is not created.Term cannot be inserted\n");
  else
  {
   temp->coef=c;
   temp->exp=e;
   temp->link=NULL;
   *start=temp;
  }
 }
 else
 {
  temp1=*start;
  while (temp1!=NULL && temp1->exp>e)
  {
   prev=temp1;
   temp1=temp1->link;
  }
  if(temp1==NULL)
  {
   temp=(struct node *)malloc(sizeof(struct node));
   if (temp==NULL)
    printf("Node is not created\n");
    
   else
   {
    temp->coef=c;
    temp->exp=e;
    temp->link=NULL;
    prev->link=temp; 
   }
  }
  else
  {
   if(temp1->exp==e)
    temp1->coef=temp1->coef+c;
   else
   {
    if(temp1==*start)
    {
     temp=(struct node *)malloc (sizeof (struct node));
     if(temp==NULL)
      printf("Node is not created\n");
     else
     {
      temp->coef=c;
      temp->exp=e;
      temp->link=*start;
      *start=temp;
     }
    }
    else
    {
     temp=(struct node *)malloc(sizeof(struct node));
     if (temp==NULL)
      printf("node is not created\n");
     else
     {
      temp->coef=c;
      temp->exp=e;
      temp->link=temp1;
      prev->link=temp;
     }
    }
   } 
  }
 }

}
void traverse(struct node *start)
{
 struct node *temp;
 temp=start;
 if (temp==NULL)
  printf("Empty polynomial\n");
 else
 {
  while(temp!=NULL)
  {
   printf("+  %d X ^%d ",temp->coef,temp->exp);
   temp=temp->link;
  }
  printf("\n");
 }
 

}
void poly_add(struct node** start_p,struct node **start_q,struct node** start_r)
{
 int c,e;
 struct node *pptr,*qptr;
 *start_r=NULL;
 pptr=*start_p;
 qptr=*start_q;
 while(pptr!=NULL && qptr!=NULL)
 {
  if (pptr->exp==qptr->exp)
  {
   c=pptr->coef+qptr->coef;
   e=pptr->exp;
   insert_term(start_r,c,e);
   pptr=pptr->link;
   qptr=qptr->link;
  }
  else
  {
   if (pptr->exp>qptr->exp)
   {
    c=pptr->coef;
    e=pptr->exp;
    insert_term(start_r,c,e);
    pptr=pptr->link;
   }
   else
   {
    c=qptr->coef;
    e=qptr->exp;
    insert_term(start_r,c,e);
    qptr=qptr->link;
   }
  }
 }
 while(pptr!=NULL)
 {
  c=pptr->coef;
  e=pptr->exp;
  insert_term(start_r,c,e);
  pptr=pptr->link;
 }
 while (qptr!=NULL)
 {
  c=qptr->coef;
  e=qptr->exp;
  insert_term(start_r,c,e);
  qptr=qptr->link;
 }
 
}
void poly_pdt(struct node ** start_p,struct node **start_q,struct node** start_r)
{
 int c,e;
 struct node *pptr,*qptr;
 *start_r=NULL;
 pptr=*start_p;
 qptr=*start_q;
 if (*start_p==NULL && *start_q==NULL)
  printf("\n Multiplication of polynomial is not possible\n");
 else
 {
  while(pptr!=NULL)
  {
   qptr=*start_q;
   while(qptr!=NULL)
   {
    c=pptr->coef*qptr->coef;
    e=pptr->exp+qptr->exp;
    insert_term(start_r,c,e);
    qptr=qptr->link;
   }
   pptr=pptr->link;
  }
 }
}

Output