How do I add 2 Polynomials

Question

I have a school project that I have almost completed, but I am totally stuck on one part.
The overall project is to write a program that reads in 2 polynomials from the user, sorts them in to 2 linked lists and then traverses those lists and adds the 2 polynomials, saving the sum in a 3rd polynomial. I have completed the code for the reading and list sorting, but I am stuck on traversing the list and adding the polynomials.
These are my guidelines:
Set up traversing references to termNodes for both polynomials p and q that point to the first
terms of each and advance through each. Set up reference to the sum r that always points to the
last added term.
If the exponent of p?s term is equal to the exponent of q?s term, add the coefficients and append
this new term to polynomial r (insert it ?after? the traversing reference of r and update this traversing
reference to this latest term.) Advance both p?s and q?s traversing references.
If the exponent of p?s term is less than the exponent of q?s term, add a copy of q?s term to r. Advance q?s traversing reference.
If the exponent of p?s term is greater than the exponent of q?s term, add a copy of p?s term to r.
Advance p?s traversing reference.
When one (or both) of p?s and q?s traversing pointers is null, write two loops that add a copy of the
remaining terms from p or q (you do not know which traversal is complete, so two loops are
required) to r.
I am just totally lost on this. Any code, pointers, anything that can point me in the right direction would be much appreciated.
If it helps, my other code is below
package linkedList;
public class termNode implements Comparable
private int coefficient;
private int exponent;
private termNode next;
//CONSTRUCTOR WITH PARAMETERS
public termNode(int c, int e)
coefficient = c;
exponent = e;
next = null;
//COPY CONSTRUCTOR
public termNode(termNode otherNode)
coefficient = otherNode.coefficient;
exponent = otherNode.exponent;
//OVERRIDE toString AND RETURN VALUES
public String toString()
     if (exponent == 0)
          return coefficient + " ";
     else if (exponent == 1)
          return coefficient + "x ";
     else
          return coefficient + "x^" + exponent + " ";
//COMPARE EXPONENTS:     RETURN 0 IF EQUAL, NEGATIVE IF THIS OBJECT IS LESS THAN
//OTHER OBJECT AND POSITIVE IF THIS OBJECT IS GREATER THAN OTHER OBJECT
public int compareTo (Object other)
if (exponent==((termNode) other).exponent)
          return 0;
else if (exponent < ((termNode) other).exponent)
          return -1;
else
          return 1;
//MUTATOR METHOD FOR COEFFICIENT
public void setCoefficient(int c)
coefficient = c;
public int getCoefficient()
return coefficient;
//MUTATOR METHOD FOR EXPONENT
public void setExponent(int e)
exponent = e;
public int getExponent()
return exponent;
//MUTATOR METHOD FOR NEXT
public void setNext(termNode n)
next = n;
public termNode getNext()
return next;
package linkedList;
import java.util.Scanner;
public class polynomial
private termNode head;
//DEFAULT CONSTRUCTOR CREATES EMPTY LIST
public polynomial()
head = null;
//READ INPUT FROM USER
public void readPolynomial()
int a = 0;
int b = 1;
Scanner kbInput = new Scanner(System.in);
System.out.println("Enter 0 and 0 to end.");
System.out.print("coefficient: ");
kbInput.skip("\\s*");//SKIPS LEADING WHITE SPACE
a = kbInput.nextInt();//READS FIRST VALUE IN TO a
kbInput.nextLine(); //SKIPS REMAINDER OF INPUT LINE
System.out.print("exponent: ");
kbInput.skip("\\s*");//SKIPS LEADING WHITE SPACE
b = kbInput.nextInt();//READS SECOND VALUE IN TO b
kbInput.nextLine(); //SKIPS REMAINDER OF INPUT LINE
while (a!=0)
termNode newTerm = new termNode(a,b);
insert(newTerm);
System.out.println("Enter 0 and 0 to end.");
System.out.print("coefficient: ");
kbInput.skip("\\s*");//SKIPS LEADING WHITE SPACE
a = kbInput.nextInt();//READS FIRST VALUE IN TO COEFFICIENT
kbInput.nextLine(); //SKIPS REMAINDER OF INPUT LINE
System.out.print("exponent: ");
kbInput.skip("\\s*");//SKIPS LEADING WHITE SPACE
b = kbInput.nextInt();//READS SECOND VALUE IN TO EXPONENT
kbInput.nextLine(); //SKIPS REMAINDER OF INPUT LINE
public void insert(termNode newNode)
termNode prev = null;
termNode cur = head;//CUR POINTS TO FIRST ITEM IN LIST (HEAD)
while (cur!=null && (newNode.compareTo(cur)>0))//TRAVERSE LIST WHILE CUR IS NOT NULL AND
{                                              //newNode EXPONENT IS GREATER THAN cur EXPONENT
          prev = cur;
          cur = cur.getNext();
if (prev==null)//INSERT AT BEGINNING OF LIST
          newNode.setNext(head);
          head = newNode;
else//INSERT IN LIST BASED ON PREVIOUS TRAVERSING
          newNode.setNext(cur);
          prev.setNext(newNode);
//System.out.println(cur.getNext());
//DISPLAY "0" FOR EMPTY LIST, OTHERWISE TRAVERSE AND DISPLAY POLYNOMIAL
public void display()
if (head==null)
          System.out.println("0");
else
          for (termNode cur=head; cur!=null; cur = cur.getNext())
                    System.out.print(cur);
}

Answer 1

My first bit of advice is to lose those awful star-boxed comments. Atrocious.
Just saw the second class. You have, by a wide margin, the very worst commenting style I've ever seen.
Wait for it - "My teacher tells me we have to comment our code or s/he'll take off points, so I have to keep them." Oy.
You aren't following the Sun standards for Java coding, either. I'd recommend learning them.
The rest ain't so bad.
So your two problems - list traversal and addition. We'll start with the second one. Do you know how to add two polynomials? Do you know the rules for adding two monomials? If I gave you these, what would the answer be?
p1(x) = 4x^2
p2(x) = 5x^3
p1(x) + p2(x) = ?
How 'bout
p3(x) = 5x^2 + 4
p4(x) = 10x^100 - x^2
p3(x) + p4(x) = ?
If you can figure these out, the coding should be clearer.
As for the list, your "next" and "head" data members lead me to believe that you intend to do your own linked list. Do you know how to do that? Why aren't you considering the Java collections?
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