public class Poly {
   //OVERVIEW:
	...
   private int[ ] trms;
   private int deg;

   // constructors
   public Poly ( ) {
      //EFFECTS: Initializes this to be the zero polynomial.
      trms = new int[1]; deg = 0;
   }

   public Poly (int c, int n) throws NegativeExponentException {
      //EFFECTS: If n < 0 throws NegativeExponentException else
     //initializes this to be the Poly cxn.
      if (n < 0)
         throw new NegativeExponentException("Poly(int,int) constructor");
      if (c == 0) { trms = new int[1]; deg = 0; return; }
      trms = new int[n+1];
      for (int i = 0; i < n; i++) trms[i] = 0;
      trms[n] = c;
      deg = n;
   }

   private Poly (int n) { trms = new int[n+1]; deg = n; }

   // methods
   public int degree ( ) {
      //EFFECTS: Returns the degree of this, i.e., the largest exponent
     //   with a non-zero coefficient. Returns 0 if this is the zero Poly.
      return deg;
   }

   public int coeff (int d) {
      //EFFECTS: Returns the coefficient of the term of this whose exponent is d.
      if (d < 0 || d > deg) return 0; else return trms[d];
   }

   public Poly sub (Poly q) throws NullPointerException {
      //EFFECTS: If q is null throws NullPointerException else
     // returns the Poly this - q.
      return add (q.minus( ));
   }

   public Poly minus ( ) {
      //EFFECTS: Returns the Poly -this.
      Poly r = new Poly(deg);
      for (int i = 0; i < deg; i++) r.trms[i] = - trms[i];
      return r;
   }