PRACTICE EXAM 2 SAMPLE ANSWERS

1.  (a)        total
                 1
         1+ 1 =  2
         2+ 2 =  4
         4+ 4 =  8
         8+ 8 = 16
        16+16 = 32
        32+32 = 64
        64+64 = 128 > 100 exit loop

        prints 128

    (b)  result
           4
           8
          16
          32
          64
         128 <- skips over 100, infinite loop, never reaches the print 
                statement and prints nothing

    (c)  i    sum
               0
         1     1    (0+1)
         4     5    (1+4)
         7    12    (5+7)
         10   22   (12+10)
         13 <- exit loop, prints 22

    (d)  i   product
               1
         10 <- exit loop, prints 1

    (e)  str = "Carnegie", length = 8
         i      charAt(i)
         1        a
         3        n
         5        g
         7        e
         9 <- exit loop, prints  ange

2.  (a)  i  j  sum  product
                       1
         1      0
            1   1      
            2               <- exit j-loop
                       1
         2      0
            1   1      
            2   3
            3               <- exit j-loop
                       3    
         3      0
            1   1      
            2   3      
            3   6    
            4               <- exit j-loop
                      18
         4                  <- exit i-loop

         prints 18

    (b)  i  j  sum  product
                0      1
         1  1   1
            2             exit j-loop
                       1
         2  1   2       
            2   4      
            3             exit j-loop
                       4
         3  1   5      
            2   7    
            3  10
            4             exit j-loop
                      40
         4                exit i-loop

          prints 40

    (c) product = 1;
        int i = 1;
        while (i < 4) {
            int sum = 0;

            int j = 1;
            while (j <= i) {
                sum +=j;
                j++;
            }

            product *= sum;
            i++;
        }
        System.out.println(product);

3. (a) score = new int[30];

   (b) for (int i = 0; i < 30; i++) {
           score[i] = (int) (Math.random() * 20) * 5 + 5;
       }

   (c) int max = score[0];
       for (int i = 1; i < 30; i++) {
           if (score[i] > max) {
               max = score[i];
           }
       }

   (d) Yes.  It must be a static method because random is called on the
       class Math, not on an object of the Math class.

4. (a)

public static int countOutliers(double[] data, 
                               double lower, double upper) {

    int count = 0;

    for (int i = 0; i < data.length; i++) {

	 if ((data[i] < lower) ||_ (data[i] > upper)) {

             count =  count + 1;
	 }

    }
    
    return count;
}

  (b)

      System.out.println("The number of outliers in pH is " +
              countOutliers(pH, 0.0, 14.0));

5. 
public class DiceGame {
   public static void main(String[] args) {

      Die die1 = new Die(6);
      Die die2 = new Die(6);

      int score = 0;
      int numRolls = 1;
      while (score < 70 && numRolls <= 10) {
         die1.roll();
         die2.roll();
         if (die1.getFaceValue() == die2.getFaceValue()) [
             score = score - 10;
             if (score < 0) {
                 score = 0;
             }
         } else {
             score = score + die1.getFaceValue() + die2.getFaceValue();
         }
         System.out.println("You rolled " + die1.getFaceValue() + " " 
                             + die2.getFaceValue() + ". Your score is " + score);
      }

      if (score >= 70 {
          System.out.println("WINNER");
      } else {
          System.out.println("LOSER");
      }
   }
}