LLpoly

#include<stdio.h>
#include<stdlib.h>
struct node
{
    int exp;
    int coeff;
    struct node *next;
};

struct node *ReadPoly();
struct node *AddPoly(struct node *p1,struct node *p2);
struct node *MultiplyPoly(struct node *p1,struct node *p2);
void Display(struct node *head);
int main()
{
    struct node *Phead,*Qhead,*Rhead;
    Phead=Qhead=Rhead=NULL;
    int c;
    printf("***FIRST POLYNOMIAL***");
    Phead=ReadPoly();
    printf("\nThe Inputted Polynomial 1 is: \n");
    Display(Phead);
    printf("\n");
    printf("\n***SECOND POLYNOMIAL***");
    Qhead=ReadPoly();
    printf("\nThe Inputted Polynomial 2 is: \n");
    Display(Qhead);
    printf("\n");
    do
    {
        printf("\n***LINKED LIST OPERATIONS***\n");
        printf("1.ADD POLYNOMIAL\n2.MULTIPLY POLYNOMIAL\n3.EXIT");
        printf("\nEnter your choice: ");
        scanf("%d",&c);
        switch(c)
        {
            case 1:
                Rhead=AddPoly(Phead,Qhead);
                printf("\nResultant Polynomial is: \n");
                Display(Rhead);
                break;
            case 2:
                Rhead=MultiplyPoly(Phead,Qhead);
                printf("Resultant Polynomial is: \n");
                Display(Rhead);
                break;
            case 3:
                printf("EXIT");
                break;
            default:
                printf("Enter valid choice(1,2,3)");
                break;
        }
    }while(c!=3);
}

struct node *ReadPoly()
{
    int terms,i,c,e;
    struct node *n,*head=NULL,*ptr;
    printf("\nEnter the number of terms: ");
    scanf("%d",&terms);
    for(i=0;i<terms;i++)
    {
        n=(struct node*)malloc(sizeof(struct node));
        printf("\nEnter the coefficient (%d): ",(i+1));
        scanf("%d",&c);
        printf("\nEnter the exponent (%d): ",(i+1));
        scanf("%d",&e);
        n->coeff=c;
        n->exp=e;
        n->next=NULL;
        if(head==NULL)
        {
            head=ptr=n;
        }
        else
        {
            ptr->next=n;
            ptr=n;
        }
        ptr->next=NULL;
    }
    return head;
}

void Display(struct node *head)
{
    struct node *ptr;
    ptr=head;
    while(ptr->next!=NULL)
    {
        printf("%d(x^%d)+",ptr->coeff,ptr->exp);
        ptr=ptr->next;
    }
    printf("%d(x^%d)",ptr->coeff,ptr->exp);
}

struct node *AddPoly(struct node *p1,struct node *p2)
{
    struct node *p,*q,*n,*head=NULL,*ptr;
    p=p1;
    q=p2;
    while(p!=NULL &&q!=NULL)
    {
        n=(struct node*)malloc(sizeof(struct node));
        n->next=NULL;
        if(p->exp==q->exp)
        {
            n->exp=p->exp;
            n->coeff=p->coeff + q->coeff;
            p=p->next;
            q=q->next;
        }
        else if(p->exp>q->exp)
        {
            n->exp=p->exp;
            n->coeff=p->coeff;
            p=p->next;
        }
        else
        {
            n->exp=q->exp;
            n->coeff=q->coeff;
            q=q->next;
        }
        if(head==NULL)
        {
            head=ptr=n;
        }
        else
        {
            ptr->next=n;
            ptr=n;
        }
    }
    while(p!=NULL)
    {
        n=(struct node*)malloc(sizeof(struct node));
        n->exp=p->exp;
        n->coeff=p->coeff;
        n->next=NULL;
        p=p->next;
        if(head==NULL)
        {
            head=ptr=n;
        }
        else
        {
            ptr->next=n;
            ptr=n;
        }
    }
    while(q!=NULL)
    {
        n=(struct node*)malloc(sizeof(struct node));
        n->exp=q->exp;
        n->coeff=q->coeff;
        n->next=NULL;
        q=q->next;
        if(head==NULL)
        {
            head=ptr=n;
        }
        else
        {
            ptr->next=n;
            ptr=n;
        }
    }
    return head;
}

struct node *MultiplyPoly(struct node *p1,struct node *p2)
{
    struct node *p,*q,*r,*n,*head,*prev;
    p=p1;
    q=p2;
    head=NULL;
    while(p!=NULL)
    {
        while(q!=NULL)
        {
            n=(struct node*)malloc(sizeof(struct node));
            n->exp=p->exp + q->exp;
            n->coeff=p->coeff * q->coeff;
            n->next=NULL;
            if(head==NULL)
            {
                head=r=n;
            }
            else
            {
                r->next=n;
                r=n;
            }
            q=q->next;
        }
        p=p->next;
        q=p2;
    }
    p=head;
    while(p!=NULL)
    {
        prev=p;
        q=p->next;
        while(q!=NULL)
        {
            if(p->exp==q->exp)
            {
                p->coeff=p->coeff + q->coeff;
                prev->next=q->next;
                free(q);
                q=prev->next;
            }
            else
            {
                prev=q;
                q=q->next;
            }
        }
        p=p->next;
    }
    return head;
}