sgLLpolynomial.cpp

//LL of polynomial and perform operations in it
#include<iostream>
#include<string>
#define null 0
using namespace std;
struct polynode
{
   int coef,pow;
   polynode *next;
};
polynode *first,*temp,*ttemp,*poly1,*poly2,*sum,*diff,*prod,*a,*b;
void init()
{
    first=temp=ttemp=poly1=poly2=null; 
}
void insertdata(polynode*& head, int coef, int pow) 
{
    // Skip inserting zero coefficient terms
    if (coef == 0) return;

    ttemp = new polynode{coef, pow, nullptr};

    // Insert at head if list empty or new pow is greater than head pow (descending order)
    if (!head || pow > head->pow) 
    {
        ttemp->next = head;
        head = ttemp;
        return;
    }

    temp = head;
    while (temp) 
    {
        // If same power, accumulate coefficient and delete new node
        if (temp->pow == pow) 
        {
            temp->coef += coef;
            // If coefficient becomes zero, remove the node
            if (temp->coef == 0) 
            {
                // remove head
                if (temp == head) 
                {
                    polynode* toDel = head;
                    head = head->next;
                    delete toDel;
                } else {
                    // find previous to temp
                    polynode* prev = head;
                    while (prev && prev->next != temp) prev = prev->next;
                    if (prev) {
                        prev->next = temp->next;
                        delete temp;
                    }
                }
            }
            delete ttemp;
            return;
        }

        if (!temp->next || temp->next->pow < pow)
            break;
        temp = temp->next;
    }

    ttemp->next = temp->next;
    temp->next = ttemp;
}
void disp(polynode* head)
{
    while (head) {
        cout << head->coef << "x^" << head->pow;
        if (head->next) cout << " + ";
        head = head->next;
    }
    cout << "\n";
}
polynode* addPoly(polynode*p1,polynode*p2)
{
   polynode* result = null;

   // Merge-like safe approach: process while both non-null, then append remaining
   while (p1 && p2) {
       if (p1->pow > p2->pow) {
           insertdata(result, p1->coef, p1->pow);
           p1 = p1->next;
       } else if (p2->pow > p1->pow) {
           insertdata(result, p2->coef, p2->pow);
           p2 = p2->next;
       } else { // equal powers
           insertdata(result, p1->coef + p2->coef, p1->pow);
           p1 = p1->next;
           p2 = p2->next;
       }
   }

   while (p1) { insertdata(result, p1->coef, p1->pow); p1 = p1->next; }
   while (p2) { insertdata(result, p2->coef, p2->pow); p2 = p2->next; }

   return result;
}
polynode* subPoly(polynode*p1,polynode*p2)
{
  polynode* result = null;

  while (p1 && p2) {
      if (p1->pow > p2->pow) {
          insertdata(result, p1->coef, p1->pow);
          p1 = p1->next;
      } else if (p2->pow > p1->pow) {
          insertdata(result, -p2->coef, p2->pow);
          p2 = p2->next;
      } else {
          insertdata(result, p1->coef - p2->coef, p1->pow);
          p1 = p1->next;
          p2 = p2->next;
      }
  }

  while (p1) { insertdata(result, p1->coef, p1->pow); p1 = p1->next; }
  while (p2) { insertdata(result, -p2->coef, p2->pow); p2 = p2->next; }

  return result;

}

polynode* mulPoly(polynode*p1,polynode*p2)
{
   polynode* result = null;
    for ( a = p1; a != null; a = a->next) {
        for (b = p2; b != null; b = b->next) {
            int newCoef = a->coef * b->coef;
            int newPow = a->pow + b->pow;
            insertdata(result, newCoef, newPow);
        }
    }
    return result;
}

int main()
{   init();
    int n,coef,pow;
    //insert poly1
    cout<<"enter no. of terms in poly1: ";
    cin>>n;
    cout<<"\nenter terms as coef and pow\n";
    for (int i = 0; i < n; i++) {
    cin >> coef >> pow;
    insertdata(poly1, coef, pow);
    }

    //insert poly2
    cout<<"enter no. of terms in poly2: ";
    cin>>n;
    cout<<"\nenter terms as coef and pow\n";
    for (int i = 0; i < n; i++) {
    cin >> coef >> pow;
    insertdata(poly2, coef, pow);
    }


    //display original
    cout << "\nPolynomial 1: ";
    disp(poly1);
    cout << "Polynomial 2: ";
    disp(poly2);

    // Perform operations
     sum = addPoly(poly1, poly2);
     diff = subPoly(poly1, poly2);
     prod = mulPoly(poly1, poly2);
    // Display results
    cout << "\nSum: ";
    disp(sum);
    cout << "Difference: ";
    disp(diff);
    cout << "Product: ";
    disp(prod);


    return 0;

}