CSC300: Homework (MyFirstHomework)

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Uploading homework [3/4]
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Homework (MyFirstHomework) [2/4]

file:MyFirstHomeworkFor300.java [source] [doc-public] [doc-private]
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package algs11;

import java.util.Arrays;
import stdlib.*;

/**
 * This is a skeleton file for your homework. Edit the sections marked TODO. You
 * may also edit the function "main" to test your code.
 *
 * You must not change the declaration of any method. This will be true of every
 * skeleton file I give you.
 *
 * For example, you will get zero points if you change the line
 * 
 * <pre>
 *     public static int minPosition (double[] list) {
 * </pre>
 * 
 * to something like
 * 
 * <pre>
 *     public static double minPosition (double[] list) {
 * </pre>
 * 
 * or
 * 
 * <pre>
 *     public static int minPosition (double[] list, int i) {
 * </pre>
 * 
 * Each of the functions below is meant to be SELF CONTAINED. This means that
 * you should use no other functions or classes. You should not use any HashSets
 * or ArrayLists, or anything else! In addition, each of your functions should
 * go through the argument array at most once.  The only exception to this the java
 * Math.abs.  You can use the Math.abs function to compute the absolute value.
 */
public class MyFirstHomeworkFor300 {

  /**
   * minValue returns the minimum value in an array of doubles. You can assume
   * the array is nonempty and has no duplicates. Your solution must go
   * through the array exactly once. Your solution must not call any other
   * functions. Here are some examples (using "==" informally):
   *
   * <pre>
   *   -7  == minValue (new double[] { -7 })
   *    1  == minValue (new double[] { 1, 7, 8, 11 })
   *   -7  == minValue (new double[] { 1, -4, -7, 7, 8, 11 })
   *   -13 == minValue (new double[] { -13, -4, -7, 7, 8, 11 })
   *   -13 == minValue (new double[] { 1, -4, -7, 7, 8, 11, -13 })
   * </pre>
   */
  public static double minValue (double[] list) {
    return StdRandom.uniform (); //TODO: fix this
  }

  /**
   * minPosition returns the position of the minimum value in an array of
   * doubles. The first position in an array is 0 and the last is the
   * array.length-1.
   *
   * You can assume the array is nonempty and has no duplicates. Your solution
   * must go through the array exactly once. Your solution must not call any
   * other functions. Here are some examples (using "==" informally):
   *
   * <pre>
   *   0 == minPosition(new double[] { -7 })
   *   2 == minPosition(new double[] { 1, -4, -7, 7, 8, 11 })
   *   0 == minPosition(new double[] { -13, -4, -7, 7, 8, 11 })
   *   6 == minPosition(new double[] { 1, -4, -7, 7, 8, 11, -9 })
   * </pre>
   */
  public static int minPosition (double[] list) {
    return StdRandom.uniform (100); //TODO: fix this
  }

  /**
   * distanceBetweenMinAndMax returns difference between the minPosition and
   * the maxPosition in an array of doubles.
   *
   * You can assume the array is nonempty and has no duplicates. Your solution
   * must go through the array exactly once. Your solution must not call any
   * other functions. Here are some examples (using "==" informally):
   *
   * <pre>
   *   0 == distanceBetweenMinAndMax(new double[] { -7 })                      // -7,-7 are the min and max
   *   3 == distanceBetweenMinAndMax(new double[] { 1, -4, -7, 7, 8, 11 }),    // -7,11
   *   5 == distanceBetweenMinAndMax(new double[] { -13, -4, -7, 7, 8, 11 })   // -13,11
   *   1 == distanceBetweenMinAndMax(new double[] { 1, -4, -7, 7, 8, 11, -9 }) // -9,11
   * </pre>
   */
  public static int distanceBetweenMinAndMax (double[] list) {
    return StdRandom.uniform (100); //TODO: fix this
  }

  /*
   * A main function for debugging -- change the name to "main" to run it (and
   * rename the existing main method to something else). Change the test as
   * appropriate.
   */
  public static void main1 (String[] args) {
    Trace.drawStepsOfMethod ("minValue");
    Trace.run ();
    testMinValue (9, "11 21 9 31 41");
  }
  
  /**
   * A test program, using private helper functions. See below. To make typing
   * tests a little easier, I've written a function to convert strings to
   * arrays. See below.
   */
  public static void main (String[] args) {
    // for minValue: array must be nonempty with unique elements
    testMinValue (-7, "1 -4 -7 7 8 11 9 -5");
    testMinValue (-0.5, "0.2 -0.5 -0.1");
    testMinValue (9, "11 9 21 31 41");
    testMinValue (9, "11 21 9 31 41");
    testMinValue (9, "11 21 31 9 41");
    testMinValue (9, "11 21 31 41 9");
    testMinValue (9, "9 11 21 31 41");
    testMinValue (-99, "-11 -99 -21 -31 -41");
    testMinValue (-99, "-11 -21 -99 -31 -41");
    testMinValue (-99, "-11 -21 -31 -99 -41");
    testMinValue (-99, "-11 -21 -31 -41 -99");
    testMinValue (-99, "-99 -11 -21 -31 -41");
    testMinValue (11, "11");
    testMinValue (-11, "-11");
    
    // for minPosition: array must be nonempty with unique elements
    testMinPosition (2, "1 -4 -7 7 8 11 9 -5");
    testMinPosition (1, "0.2 -0.5 -0.1");
    testMinPosition (1, "11 9 21 31 41");
    testMinPosition (2, "11 21 9 31 41");
    testMinPosition (3, "11 21 31 9 41");
    testMinPosition (4, "11 21 31 41 9");
    testMinPosition (0, "9 11 21 31 41");
    testMinPosition (1, "-11 -99 -21 -31 -41");
    testMinPosition (2, "-11 -21 -99 -31 -41");
    testMinPosition (3, "-11 -21 -31 -99 -41");
    testMinPosition (4, "-11 -21 -31 -41 -99");
    testMinPosition (0, "-99 -11 -21 -31 -41");
    testMinPosition (0, "11");
    testMinPosition (0, "-11");

    // for distanceBetweenMinAndMax: array must be nonempty with unique elements
    testDistanceBetweenMinAndMax (3, "1 -4 -7 7 8 11 9 -5");
    testDistanceBetweenMinAndMax (3, "0.1 -0.4 -0.7 0.7 0.8 1.1 0.9 -0.5");
    testDistanceBetweenMinAndMax (4, "9 11 21 31 41");
    testDistanceBetweenMinAndMax (3, "11 9 21 31 41");
    testDistanceBetweenMinAndMax (2, "11 21 9 31 41");
    testDistanceBetweenMinAndMax (1, "11 21 31 9 41");
    testDistanceBetweenMinAndMax (1, "11 21 31 41 9");
    testDistanceBetweenMinAndMax (4, "9 -11 -21 -31 -41");
    testDistanceBetweenMinAndMax (3, "-11 9 -21 -31 -41");
    testDistanceBetweenMinAndMax (2, "-11 -21 9 -31 -41");
    testDistanceBetweenMinAndMax (1, "-11 -21 -31 9 -41");
    testDistanceBetweenMinAndMax (1, "-11 -21 -31 -41 9");
    testDistanceBetweenMinAndMax (0, "11");
    testDistanceBetweenMinAndMax (0, "-11");
    
    StdOut.println ("Finished tests");
  }

  /* Test functions --- lot's of similar code! */
  private static void testMinValue (double expected, String list) {
    double[] aList = doublesFromString (list);
    double actual = minValue (aList);
    if (!Arrays.equals (aList, doublesFromString (list))) {
      StdOut.format ("Failed minValue([%s]): Array modified\n", list);
    }
    if (expected != actual) {
      StdOut.format ("Failed minValue([%s]): Expecting (%.1f) Actual (%.1f)\n", list, expected, actual);
    }
  }
  private static void testMinPosition (int expected, String list) {
    double[] aList = doublesFromString (list);
    int actual = minPosition (aList);
    if (!Arrays.equals (aList, doublesFromString (list))) {
      StdOut.format ("Failed minPosition([%s]): Array modified\n", list);
    }
    if (expected != actual) {
      StdOut.format ("Failed minPosition([%s]): Expecting (%d) Actual (%d)\n", list, expected, actual);
    }
  }
  private static void testDistanceBetweenMinAndMax (int expected, String list) {
    double[] aList = doublesFromString (list);
    int actual = distanceBetweenMinAndMax (aList);
    if (!Arrays.equals (aList, doublesFromString (list))) {
      StdOut.format ("Failed distanceBetweenMinAndMax([%s]): Array modified\n", list);
    }
    if (expected != actual) {
      StdOut.format ("Failed distanceBetweenMinAndMax([%s]): Expecting (%d) Actual (%d)\n", list, expected, actual);
    }
  }

  /* A utility function to create an array of doubles from a string. */
  // The string should include a list of numbers, separated by single spaces.
  private static double[] doublesFromString (String s) {
    if ("".equals (s)) return new double[0]; // empty array is a special case
    String[] nums = s.split (" ");
    double[] result = new double[nums.length];
    for (int i = nums.length - 1; i >= 0; i--) {
      try {
        result[i] = Double.parseDouble (nums[i]);
      } catch (NumberFormatException e) {
        throw new IllegalArgumentException (String.format ("Bad argument \"%s\": could not parse \"%s\" as a double", s, nums[i]));
      }
    }
    return result;
  }
}

file:MyFirstHomeworkFor300PartTwo.java [source] [doc-public] [doc-private]
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package algs11;

import java.util.Arrays;
import stdlib.*;

/**
 * This is a skeleton file for your homework. Edit the sections marked TODO. You
 * may also edit the function "main" to test your code.
 *
 * You must not change the declaration of any method. This will be true of every
 * skeleton file I give you.
 *
 * For example, you will get zero points if you change the line
 * 
 * <pre>
 *     public static double minValue (double[] list) {
 * </pre>
 * 
 * to something like
 * 
 * <pre>
 *     public static void minValue (double[] list) {
 * </pre>
 * 
 * or
 * 
 * <pre>
 *     public static double minValue (double[] list, int i) {
 * </pre>
 * 
 * Each of the functions below is meant to be SELF CONTAINED. This means that
 * you should use no other functions or classes. You should not use any HashSets
 * or ArrayLists, or anything else! In addition, each of your functions should
 * go through the argument array at most once. The only exception to this
 * removeDuplicates, which is allowed to call numUnique and then go through the
 * array once after that.
 */
public class MyFirstHomeworkFor300PartTwo {

  /**
   * allSame returns true if all of the elements in list have the same value.
   * allSame returns false if any two elements in list have different values.
   * The array may be empty and it may contain duplicate values. 
   *
   * Your solution should contain at most one loop.  You may not use recursion.  
   * Your solution must not call any other functions. 
   * Here are some examples (using "==" informally):
   *
   * <pre>
   *     true  == allSame(new double[] { })
   *     true  == allSame(new double[] { 11 })
   *     true  == allSame(new double[] { 11, 11, 11, 11 })
   *     false == allSame(new double[] { 11, 11, 11, 22 })
   *     false == allSame(new double[] { 11, 11, 22, 11 })
   *     true  == allSame(new double[] { 22, 22, 22, 22 })
   * </pre>
   */
  public static boolean allSame (double[] list) {
    return StdRandom.bernoulli(); //TODO: fix this
  }
  
  /**
   * numUnique returns the number of unique values in an array of doubles.
   * The array may be empty and it may contain duplicate values. 
   * Unlike the previous questions, you can assume the array is sorted.
   *
   * Your solution should contain at most one loop.  You may not use recursion.  
   * Your solution must not call any other functions. 
   * Here are some examples (using "==" informally):
   *
   * <pre>
   *     0 == numUnique(new double[] { })
   *     1 == numUnique(new double[] { 11 })
   *     1 == numUnique(new double[] { 11, 11, 11, 11 })
   *     8 == numUnique(new double[] { 11, 11, 11, 11, 22, 33, 44, 44, 44, 44, 44, 55, 55, 66, 77, 88, 88 })
   *     8 == numUnique(new double[] { 11, 22, 33, 44, 44, 44, 44, 44, 55, 55, 66, 77, 88 })
   * </pre>
   */
  public static int numUnique (double[] list) {
    return StdRandom.uniform (100); //TODO: fix this
  }

  /**
   * removeDuplicates returns a new array containing the unique values in the
   * array, in the same order that they were found in the original array.  
   * There should not be any extra space in the array --- there should
   * be exactly one space for each unique element (Hint: numUnique tells you
   * how big the array should be). You may assume that the list is sorted, as
   * you did for numUnique.
   *
   * Your solution should contain at most one loop.  You may not use recursion.  
   * Your solution must not call any other functions, except numUnique.
   * Here are some examples (using "==" informally):
   *
   * <pre>
   *   new double[] { }
   *     == removeDuplicates(new double[] { })
   *   new double[] { 11 }
   *     == removeDuplicates(new double[] { 11 })
   *     == removeDuplicates(new double[] { 11, 11, 11, 11 })
   *   new double[] { 11, 22, 33, 44, 55, 66, 77, 88 }
   *     == removeDuplicates(new double[] { 11, 11, 11, 11, 22, 33, 44, 44, 44, 44, 44, 55, 55, 66, 77, 88, 88 })
   *     == removeDuplicates(new double[] { 11, 22, 33, 44, 44, 44, 44, 44, 55, 55, 66, 77, 88 })
   * </pre>
   */
  public static double[] removeDuplicates (double[] list) {
    double[] result = new double[numUnique(list)];
    // TODO: fix this
    return result; 
  }

  /*
   * A main function for debugging -- change the name to "main" to run it (and
   * rename the existing main method to something else). Change the test as
   * appropriate.
   */
  public static void main2 (String[] args) {
    Trace.drawStepsOfMethod ("removeDuplicates");
    Trace.run ();
    testRemoveDuplicates ("11 21 31 41", "11 21 31 41");
    testRemoveDuplicates ("11 21", "11 11 21");
  }

  /**
   * A test program, using private helper functions. See below. To make typing
   * tests a little easier, I've written a function to convert strings to
   * arrays. See below.
   */
  public static void main (String[] args) {
    testAllSame (true, "11 11 11 11");
    testAllSame (true, "5 5 5");
    testAllSame (false, "11 5 11 11");
    testAllSame (false, "11 11 5 11");
    testAllSame (false, "11 11 11 5");
    testAllSame (false, "5 11 11 11");
    testAllSame (false, "11 5 5 11 11");
    testAllSame (false, "11 11 5 5 11");
    testAllSame (false, "11 11 5 11 5");
    testAllSame (false, "5 5 11 11 11");
    testAllSame (false, "11 11 11 5 5");
    testAllSame (true, "11");
    testAllSame (true, "2");
    testAllSame (true, "");

    // for numUnique: array must be sorted
    testNumUnique (1, "11 11 11 11");
    testNumUnique (4, "11 21 31 41");
    testNumUnique (4, "11 11 11 21 31 31 31 31 41");
    testNumUnique (4, "11 21 21 21 31 41 41 41 41");
    testNumUnique (4, "11 11 21 21 21 31 31 41 41 41 41");
    testNumUnique (8, "11 11 11 11 21 31 41 41 41 41 41 51 51 61 71 81 81");
    testNumUnique (8, "11 21 31 41 41 41 41 41 51 51 61 71 81");
    testNumUnique (7, "11 11 11 11 21 31 41 41 41 41 41 51 51 61 71");
    testNumUnique (7, "11 21 31 41 41 41 41 41 51 51 61 71");
    testNumUnique (8, "-81 -81 -81 -81 -71 -61 -51 -51 -51 -51 -41 -41 -31 -21 -11 -11 -11");
    testNumUnique (3, "-11 -11 -11 0 0 11 11 11");
    testNumUnique (2, "0 11 11 11");
    testNumUnique (2, "-Infinity 11 11 11");
    testNumUnique (2, "11 11 11 Infinity");
    testNumUnique (1, "11 11");
    testNumUnique (1, "11");
    testNumUnique (0, "");

    // for removeDuplicates: array must be sorted
    testRemoveDuplicates ("11", "11 11 11 11");
    testRemoveDuplicates ("11 21", "11 11 21");
    testRemoveDuplicates ("11 21 31 41", "11 21 31 41");
    testRemoveDuplicates ("11 21 31 41", "11 11 11 21 31 31 31 31 41");
    testRemoveDuplicates ("11 21 31 41", "11 21 21 21 31 41 41 41 41");
    testRemoveDuplicates ("11 21 31 41", "11 11 21 21 21 31 31 41 41 41 41");
    testRemoveDuplicates ("11 21 31 41 51 61 71 81", "11 11 11 11 21 31 41 41 41 41 41 51 51 61 71 81 81");
    testRemoveDuplicates ("11 21 31 41 51 61 71 81", "11 21 31 41 41 41 41 41 51 51 61 71 81");
    testRemoveDuplicates ("11 21 31 41 51 61 71", "11 11 11 11 21 31 41 41 41 41 41 51 51 61 71");
    testRemoveDuplicates ("11 21 31 41 51 61 71", "11 21 31 41 41 41 41 41 51 51 61 71");
    testRemoveDuplicates ("-81 -71 -61 -51 -41 -31 -21 -11", "-81 -81 -81 -81 -71 -61 -51 -51 -51 -51 -41 -41 -31 -21 -11 -11 -11");
    testRemoveDuplicates ("-11 0 11", "-11 -11 -11 0 0 11 11 11");
    testRemoveDuplicates ("0 11", "0 11 11 11");
    testRemoveDuplicates ("-Infinity 11", "-Infinity 11 11 11");
    testRemoveDuplicates ("Infinity 11", "Infinity 11 11 11");
    testRemoveDuplicates ("NaN 11", "NaN 11 11 11");
    testRemoveDuplicates ("11", "11 11");
    testRemoveDuplicates ("11", "11");
    testRemoveDuplicates ("", "");
    StdOut.println ("Finished tests");
  }

  private static void testAllSame (boolean expected, String list) {
    double[] aList = doublesFromString (list);
    boolean actual = allSame (aList);
    if (!Arrays.equals (aList, doublesFromString (list))) {
      StdOut.format ("Failed allSame([%s]): Array modified\n", list);
    }
    if (expected != actual) {
      StdOut.format ("Failed allSame([%s]): Expecting (%b) Actual (%b)\n", list, expected, actual);
    }
  }
  private static void testNumUnique (int expected, String list) {
    double[] aList = doublesFromString (list);
    int actual = numUnique (aList);
    if (!Arrays.equals (aList, doublesFromString (list))) {
      StdOut.format ("Failed numUnique([%s]): Array modified\n", list);
    }
    if (expected != actual) {
      StdOut.format ("Failed numUnique([%s]): Expecting (%d) Actual (%d)\n", list, expected, actual);
    }
  }
  private static void testRemoveDuplicates (String expected, String list) {
    double[] aList = doublesFromString (list);
    double[] actual = removeDuplicates (aList);
    if (!Arrays.equals (aList, doublesFromString (list))) {
      StdOut.format ("Failed removeDuplicates([%s]): Array modified\n", list);
    }
    double[] aExpected = doublesFromString (expected);
    // != does not do what we want on arrays
    if (!Arrays.equals (aExpected, actual)) {
      StdOut.format ("Failed removeDuplicates([%s]): Expecting (%s) Actual (%s)\n", list, Arrays.toString (aExpected), Arrays.toString (actual));
    }
  }

  /* A utility function to create an array of doubles from a string. */
  // The string should include a list of numbers, separated by single spaces.
  private static double[] doublesFromString (String s) {
    if ("".equals (s)) return new double[0]; // empty array is a special case
    String[] nums = s.split (" ");
    double[] result = new double[nums.length];
    for (int i = nums.length - 1; i >= 0; i--) {
      try {
        result[i] = Double.parseDouble (nums[i]);
      } catch (NumberFormatException e) {
        throw new IllegalArgumentException (String.format ("Bad argument \"%s\": could not parse \"%s\" as a double", s, nums[i]));
      }
    }
    return result;
  }
}

Uploading homework [3/4]

After you have completed the assignment, save your work in eclipse and use drag-and-drop to upload the file to D2L.

hw-file-put1
hw-file-put2
hw-file-put3
hw-file-put4

If drag-and-drop does not work, you can use an alternative method, shown below.

Be very careful to upload a .java file from the src directory.

Do not upload a .class file from the bin directory.

hw-file-put5
hw-file-put6

How to talk about code via email [4/4]

If you want advice about an error, send me email, doing one of the following.

If you have a problem getting a program to work and you want me to look at some of your code in more detail, send me email with the following three things.

  1. Your java file as an attachment.

  2. A description of how the output of the program is different from what you expected.

  3. The output of your program, if it runs.


Revised: 2008/03/17 13:01