CS 455 Midterm 1 Solution

Part A.

Part B. 5 5

Problem 2

2. A
3. D
6. B
7. C
9. B
10. A
11. C
12. B
13. D
15. D

Part A. input data: 1 2 3<eof>
return value of isIncrOrder(vals): true

Part B. input data: 2 1 1 3<eof>
return value: false

Part C. New code shown in bold.

public static boolean hasAdjacentPair(Scanner in) {

   int last;    // needs to be defined outside of the blocks
   boolean foundPair = false;

   if (in.hasNextInt()) { last = in.nextInt(); }

   while (in.hasNextInt()) {
      int val1 = in.nextInt();
      int val2 = in.nextInt();
      if (val1 == val2 last) { foundPair = true; }
      last = val1;
   }
   return foundPair;
}

Problem 4
There are several different correct solutions. Here are two of them.

mkdir 09-06
cd 09-06
cp $ASNLIB/public/09-06/* .

mkdir 09-06
cp $ASNLIB/public/09-06/* 09-06

Problem 5

Solution shown in bold. There are a few variations on this solution. A solution that stored all the temperatures (and involved one or more loops) could get most of the points.

public class TempStats {
   public static final int MIN = -100;
   public static final int MAX = 150;
   public static final int NO_TEMPS = MIN - 1;
   
   private int high;
   private int low;
   private int total;
   private int sum;
   private int [] counts;
   
   
   public TempStats() {
   
      high = MIN - 1;
      low = MAX + 1;
      total = 0;
      sum = 0;
      counts = new int[MAX - MIN + 1];
   
   }
   
   public void add(int temp) {
     
      if (temp > high) { high = temp; }
      if (temp < low) { low = temp; }
      total ++;
      sum += temp;
      counts[temp - MIN]++;
   
   }
   
   public double getAverage() {
   
      if (total == 0) { return NO_TEMPS; }
      return sum / (double) total;
   
   }
   
   public int getLow() {
   
      if (total == 0) { return NO_TEMPS; }
      return low;
   
   }
   
   public int getHigh() {
   
      if (total == 0) { return NO_TEMPS; }
      return high;
   
   }
   
   public int getNumOccur(int temp) {
   
      assert (MIN <= temp && temp <= MAX);
      return counts[temp-MIN];
   
   }
}

Problem 6

public static int removeNegatives(int[] nums, int size) {
   int dest = 0;
   for (int source = 0; source < size; source++) {
      if (nums[source] >= 0) {
         nums[dest] = nums[source];
         dest++;
      }
   }
   return dest;
   // dest is the number of values we moved (i.e., number of non-negative values)
}