Question

Implement Polynomial Linked List multiply method which multiply two polynomial and returns the product as a new polynomial. - It’s an instance method which called by a polynomial and takes second polynomial as the parameter pl. It should correctly multiply two polynomials together and returns this product polynomial.

//please see the given code below

public class PolynomialLinkedlist{
   private static class PNode{
      private int coe;
      private int exp;
      private PNode next;
      public PNode(int c, int e){
         this(c, e, null);
      }
      public PNode(int c, int e, PNode n){
         coe = c;
         exp = e;
         next = n;
      }
      public void setCoe(int c){ coe = c;}
      public void setExp(int e){ exp = e;}
      public void setNext(PNode n){ next = n;}
      public int getCoe(){ return coe;}
      public int getExp(){ return exp;}
      public PNode getNext(){ return next;}
   }
   private PNode head;
   public PolynomialLinkedlist(){
      head = null;
   }
   private void add(int c, int e){
      PNode tempn = new PNode(c, e, head);
      head = tempn;
   }
   public void removeDuplicate(){
      if (head == null) return;
      PNode lookUp, checkPrev;
      lookUp = checkPrev = head;
      while (lookUp.getNext() != null){
         while (checkPrev.getNext() != null){
             if (checkPrev.getNext().getExp() == lookUp.getExp()){//found a duplicate
                //lookUp.coe += checkPrev.next.coe;
                lookUp.setCoe(lookUp.getCoe() + checkPrev.getNext().getCoe());
                checkPrev.setNext(checkPrev.getNext().getNext());
             }
             else checkPrev = checkPrev.getNext();
         }
         lookUp = lookUp.getNext();
         checkPrev = lookUp;
      }              
   }
   public PolynomialLinkedlist add(PolynomialLinkedlist pl){
      PNode addTerm = this.head;
      PolynomialLinkedlist ans = new PolynomialLinkedlist();
      for (int i = 0; i < 2; i++){
         while (addTerm != null){
            ans.add(addTerm.getCoe(), addTerm.getExp());
            addTerm = addTerm.next;
         }
         addTerm = pl.head;
      }
      ans.removeDuplicate();
      return ans;        
   }
   public PolynomialLinkedlist multiply(PolynomialLinkedlist pl){
      PolynomialLinkedlist ans = new PolynomialLinkedlist();
      return ans;        
   }
   public void print(){
      if (head == null){
         System.out.println();
         return;
      }
      removeDuplicate();
      PNode temp = head;
      while (temp.getNext() != null){
         if (temp.getCoe() != 0){
            System.out.print("(" + temp.getCoe() + ")");
            if (temp.getExp() != 0){
               System.out.print("X^" + temp.exp);
            }
            System.out.print(" + ");
         }
         temp = temp.next;
      }
      if (temp != null){
         System.out.print(temp.coe);
         if (temp.exp != 0) System.out.print("X^" + temp.exp);
         System.out.println();
      }

   }
   public static void main(String argc[]){
      PolynomialLinkedlist pn1 = new PolynomialLinkedlist();
      PolynomialLinkedlist pn2 = new PolynomialLinkedlist();
      pn1.add(1, 2);
      pn1.add(2, 3);
      pn2.add(1, 0);
      pn2.add(5, 1);
      pn2.add(-6, 1);
      pn2.add(4, 2);
      System.out.print("Polynomial 1: ");
      pn1.print();
      System.out.print("Polynomial 2: ");
      pn2.print();
      PolynomialLinkedlist sum = pn1.add(pn2);
      PolynomialLinkedlist prod = pn1.multiply(pn2);
      System.out.print("Sum: ");
      sum.print();   
      System.out.print("Product: ");
      prod.print();   
   }
}

Answer 1

Screenshot of the code that is to be added(rest the entire program is the same and untouched):

The Output Obtained:

The Code Used:

public class PolynomialLinkedlist{
    private static class PNode{
        private int coe;
        private int exp;
        private PNode next;
        public PNode(int c, int e){
            this(c, e, null);
        }
        public PNode(int c, int e, PNode n){
            coe = c;
            exp = e;
            next = n;
        }
        public void setCoe(int c){ coe = c;}
        public void setExp(int e){ exp = e;}
        public void setNext(PNode n){ next = n;}
        public int getCoe(){ return coe;}
        public int getExp(){ return exp;}
        public PNode getNext(){ return next;}
    }
    private PNode head;
    public PolynomialLinkedlist(){
        head = null;
    }
    private void add(int c, int e){
        PNode tempn = new PNode(c, e, head);
        head = tempn;
    }
    public void removeDuplicate(){
        if (head == null) return;
        PNode lookUp, checkPrev;
        lookUp = checkPrev = head;
        while (lookUp.getNext() != null){
            while (checkPrev.getNext() != null){
                if (checkPrev.getNext().getExp() == lookUp.getExp()){//found a duplicate
                    //lookUp.coe += checkPrev.next.coe;
                    lookUp.setCoe(lookUp.getCoe() + checkPrev.getNext().getCoe());
                    checkPrev.setNext(checkPrev.getNext().getNext());
                }
                else checkPrev = checkPrev.getNext();
            }
            lookUp = lookUp.getNext();
            checkPrev = lookUp;
        }
    }
    public PolynomialLinkedlist add(PolynomialLinkedlist pl){
        PNode addTerm = this.head;
        PolynomialLinkedlist ans = new PolynomialLinkedlist();
        for (int i = 0; i < 2; i++){
            while (addTerm != null){
                ans.add(addTerm.getCoe(), addTerm.getExp());
                addTerm = addTerm.next;
            }
            addTerm = pl.head;
        }
        ans.removeDuplicate();
        return ans;
    }
    public PolynomialLinkedlist multiply(PolynomialLinkedlist pl){
        PolynomialLinkedlist ans = new PolynomialLinkedlist();  //this will store our answer.
        PNode temp1 = this.head;  //this will be used to iterate through the first polynomial.
        while(temp1 != null)
        {
            PNode temp2 = pl.head; //this will be used to iterate through the second polynomial.
            //now when two polynomials are multiplied every term in the first polynomial is multiplied with every term with every other term
            //of the second polynomial. That's why we have used a nested loop.
            while(temp2!=null)
            {
                //Now when two independent terms of a polynomial are multiplied two things happens:
                //the coefficient gets multiplied.
                //and the exponents are added.
                ans.add(temp1.getCoe()*temp2.getCoe(),temp1.getExp()+temp2.getExp());
                temp2 = temp2.next;  //iterating through the second polynomial.
            }
            temp1 = temp1.next; //iterating through the first polynomial.
        }
        ans.removeDuplicate(); //removing the duplicates.
        return ans;
    }
    public void print(){
        if (head == null){
            System.out.println();
            return;
        }
        removeDuplicate();
        PNode temp = head;
        while (temp.getNext() != null){
            if (temp.getCoe() != 0){
                System.out.print("(" + temp.getCoe() + ")");
                if (temp.getExp() != 0){
                    System.out.print("X^" + temp.exp);
                }
                System.out.print(" + ");
            }
            temp = temp.next;
        }
        if (temp != null){
            System.out.print(temp.coe);
            if (temp.exp != 0) System.out.print("X^" + temp.exp);
            System.out.println();
        }

    }
    public static void main(String argc[]){
        PolynomialLinkedlist pn1 = new PolynomialLinkedlist();
        PolynomialLinkedlist pn2 = new PolynomialLinkedlist();
        pn1.add(1, 2);
        pn1.add(2, 3);
        pn2.add(1, 0);
        pn2.add(5, 1);
        pn2.add(-6, 1);
        pn2.add(4, 2);
        System.out.print("Polynomial 1: ");
        pn1.print();
        System.out.print("Polynomial 2: ");
        pn2.print();
        PolynomialLinkedlist sum = pn1.add(pn2);
        PolynomialLinkedlist prod = pn1.multiply(pn2);
        System.out.print("Sum: ");
        sum.print();
        System.out.print("Product: ");
        prod.print();
    }
}

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