CS99

Final Exam: Solutions

Tracing Output

int n = 6;
int y = 13;
int d = 1;
while ( y > 0 ) {
       d = (n*y)%7;
       if ( d < 5 )
         y/=2;
      else
         n+=d*y;
}
System.out.println();  

Part 2: Class Definition

class Circle {
   private double radius; // the radius of the circle
   private static final double PI = Math.PI; // constant of the class
   // Default constructor
   Circle( ______________ ) {
      setRadius( 0.0 );
   }

   // Constructor
   Circle ( double r ) {
      setRadius( r );
   }

   // Return the area of the circle
   public double area() {
      return PI*radius*radius;
   }

   // Return the circumference of the circle
   public double circumference() {
      return 2*PI*radius;
   }

   // Assign the radius a new value based on the double parameter.
   // If the parameter is invalid, set the radius to 0.
   public void setRadius( double newRadius ) {
      if ( newRadius >= 0 )
         radius = newRadius;
      else
         radius = 0.0;
   }

   // Return the radius of the circle
   public double getRadius( _______________ ) {
      return radius;
   }

}

TokenReader in = new TokenReader( System.in );
int n = in.readInt();
int i = 1;
while ( i <= n ) {
   int j = 1;
   while ( j <= i ) {
      System.out.print("*");
      j++;
   }
   System.out.print("\t");
   i++;
}

Part 4: Methods

1. static boolean isPrime( int p ) {
      int factor = 2;
      boolean isPrime = true;
      while ( factor < Math.sqrt( p ) && isPrime ) {
         if ( p%factor == 0 )
            isPrime = false;
         factor++;
      }
     return isPrime && p > 1;
   }
   
2. Triangle t = new Triangle( 6, 6, 6 );
   if ( t.isRight() && t.isEquilateral() )
      System.out.println("Wow!");
   
   BONUS: The message is *not* printed.