Clean up and add ch 22 exercises

Author: HarryDulaney

ch_22/Exercise22_09.java

@@ -1,14 +1,85 @@
 package ch_22;
 
+import javafx.geometry.Point2D;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Scanner;
+import java.util.stream.Collectors;
+
 /**
  * **22.9 (Geometry: gift-wrapping algorithm for finding a convex hull) Section 22.10.1
  * introduced the gift-wrapping algorithm for finding a convex hull for a set of
- * points. Assume that the Java’s coordinate system is used for the points. Implement the algorithm using the following method:
+ * points. Assume that the Java’s coordinate system is used for the points.
+ * Implement the algorithm using the following method:
  * // Return the points that form a convex hull
  * public static ArrayList<Point2D> getConvexHull(double[][]s)
  * Point2D is defined in Section 9.6.
  * Write a test program that prompts the user to enter the set size and the points
- * and displays the points that form a convex hull.Here is a sample run:
+ * and displays the points that form a convex hull.
+ * Here is a sample run:
+ * <p>
+ * How many points are in the set? 6
+ * Enter 6 points: 1 2.4 2.5 2 1.5 34.5 5.5 6 6 2.4 5.5 9
+ * The convex hull is
+ * (1.5, 34.5) (5.5, 9.0) (6.0, 2.4) (2.5, 2.0) (1.0, 2.4)
  */
 public class Exercise22_09 {
+    public static void main(String[] args) {
+        Scanner scanner = new Scanner(System.in);
+        System.out.print("How many points are in the set? ");
+        int numPoints = scanner.nextInt();
+        System.out.print("Enter " + numPoints + " points: ");
+
+        double[][] points = new double[numPoints][2];
+
+        for (int i = 0; i < points.length; i++) {
+            for (int j = 0; j < 2; j++) {
+                points[i][j] = scanner.nextDouble();
+            }
+        }
+        scanner.close();
+        System.out.println("The convex hull is " + getConvexHull(points));
+
+    }
+
+
+    public static ArrayList<Point2D> getConvexHull(double[][] s) {
+        int n = s.length;
+        // map matrix into List of Point2D's
+        List<Point2D> S = Arrays.stream(s).map(points -> new Point2D(points[0], points[1])).collect(Collectors.toList());
+        // Created list to hold the points in the convex hull
+        ArrayList<Point2D> H = new ArrayList<>();
+        // Find the leftmost point
+        int l = 0;
+        for (int i = 1; i < n; i++)
+            if (S.get(i).getX() < S.get(l).getX()) {
+                l = i;
+            }
+
+        int p = l, q;
+        do {
+            H.add(S.get(p));
+
+            q = (p + 1) % n;
+
+            for (int i = 0; i < n; i++) {
+                if (getOrientation(S.get(p), S.get(i), S.get(q)) == -1) {
+                    q = i;
+                }
+            }
+            p = q;
+
+        } while (p != l);
+
+        return H;
+    }
+
+    public static int getOrientation(Point2D p, Point2D q, Point2D r) {
+        double val = (q.getY() - p.getY()) * (r.getX() - q.getX()) - (q.getX() - p.getX()) * (r.getY() - q.getY());
+
+        if (val == 0) return 0;
+        return (val > 0) ? 1 : -1;
+    }
 }

ch_22/Exercise22_10.java

@@ -1,10 +1,31 @@
 package ch_22;
 
+import ch_22.exercise22_08.Exercise22_08;
+
+import java.io.File;
+import java.io.RandomAccessFile;
+
 /**
  * 22.10 (Number of prime numbers) Programming Exercise 22.8 stores the prime numbers in a file named PrimeNumbers.dat.
  * Write a program that finds the number of prime numbers that are less than or equal to 10, 100, 1,000, 10,000,
  * 100,000, 1,000,000, 10,000,000, 100,000,000, 1,000,000,000, and
  * 10,000,000,000. Your program should read the data from PrimeNumbers.dat
  */
 public class Exercise22_10 {
+    private static final String[] packageParts = Exercise22_08.class.getPackage().getName().split("\\.");
+    private static final String PATH = packageParts[0] + File.separator + packageParts[1] + File.separator + "PrimeNumbers.dat";
+
+    public static void main(String[] args) {
+        try {
+            File dataFile = new File(PATH);
+            RandomAccessFile randomAccessFile = new RandomAccessFile(dataFile, "r");
+            long count = 0;
+            for (long i = 10; i <= 10_000_000_000L; i *= 10) {
+
+            }
+
+        } catch (Exception e) {
+            System.out.println("Exception occurred: " + e.getLocalizedMessage());
+        }
+    }
 }

ch_22/exercise22_08/PrimeNumbers.dat

@@ -6,6 +6,9 @@
 import java.io.RandomAccessFile;
 
 /**
+ * The prime number for Exercise 22 08 are stored in a file as bytes, so in order to
+ * evaluate the contents of the file we use this Test program to read the file and print the results.
+ * <p>
  * Integration Test will print out the prime numbers from PrimeNumbers.dat
  */
 public class Test {

ch_22/exercise22_08/Test.java

@@ -39,7 +39,6 @@ public static void main(String[] args) {
         System.out.println("list1: " + list1);
         System.out.println("list2: " + list2);
 
-
         System.out.println("list1.addAll(list2) result: ");
         list1.addAll(list2);
         System.out.println("list1: " + list1);