> ## Documentation Index
> Fetch the complete documentation index at: https://v1-learn.neoartd.my.id/llms.txt
> Use this file to discover all available pages before exploring further.

#  Basics and Printing

> 16 assignments

## 138. Basic Arrays 0 - [Link](https://programmingbydoing.com/a/basic-arrays-0.html)

<Tabs>
  <Tab title="Task">
    Create an array that can hold ten integers. Fill up each slot of the array with the number -113. Then display the contents of the array on the screen.

    *Do not* use a loop. Also, do not use any variable for the index; you must use literal numbers to refer to each slot.

    **Sample Output**

    ```bash theme={null}
    Slot 0 contains a -113
    Slot 1 contains a -113
    Slot 2 contains a -113
    Slot 3 contains a -113
    Slot 4 contains a -113
    Slot 5 contains a -113
    Slot 6 contains a -113
    Slot 7 contains a -113
    Slot 8 contains a -113
    Slot 9 contains a -113
    ```
  </Tab>

  <Tab title="Answer">
    ```java BasicArrays0.java theme={null}
    public class BasicArrays0 {
        public static void main(String[] args) {
            int[] arr = new int[10];
            arr[0] = -113;
            arr[1] = -113;
            arr[2] = -113;
            arr[3] = -113;
            arr[4] = -113;
            arr[5] = -113;
            arr[6] = -113;
            arr[7] = -113;
            arr[8] = -113;
            arr[9] = -113;

            System.out.println("Slot 0 contains a " + arr[0]);
            System.out.println("Slot 1 contains a " + arr[1]);
            System.out.println("Slot 2 contains a " + arr[2]);
            System.out.println("Slot 3 contains a " + arr[3]);
            System.out.println("Slot 4 contains a " + arr[4]);
            System.out.println("Slot 5 contains a " + arr[5]);
            System.out.println("Slot 6 contains a " + arr[6]);
            System.out.println("Slot 7 contains a " + arr[7]);
            System.out.println("Slot 8 contains a " + arr[8]);
            System.out.println("Slot 9 contains a " + arr[9]);
        }
    }
    ```
  </Tab>
</Tabs>

## 139. Basic Arrays 1 - [Link](https://programmingbydoing.com/a/basic-arrays-1.html)

<Tabs>
  <Tab title="Task">
    Create an array that can hold ten integers. Fill up each slot of the array with the number -113. Then display the contents of the array on the screen.

    This time, you *must* use a loop, to put the values in the array and also to display them. Also, in the condition of your loop, you should *not* count up to a literal number. Instead you should use the `length` field of your array.

    **Sample Output**

    ```bash theme={null}
    Slot 0 contains a -113
    Slot 1 contains a -113
    Slot 2 contains a -113
    Slot 3 contains a -113
    Slot 4 contains a -113
    Slot 5 contains a -113
    Slot 6 contains a -113
    Slot 7 contains a -113
    Slot 8 contains a -113
    Slot 9 contains a -113
    ```
  </Tab>

  <Tab title="Answer">
    ```java BasicArrays1.java theme={null}
    public class BasicArrays1 {
        public static void main(String[] args) {
            int[] arr = new int[10];
            for (int i = 0; i < arr.length; i++) {
                arr[i] = -113;
                System.out.println("Slot " + i + " contains a " + arr[i]);
            }
        }
    }
    ```
  </Tab>
</Tabs>

## 140. Basic Arrays 2 - [Link](https://programmingbydoing.com/a/basic-arrays-2.html)

<Tabs>
  <Tab title="Task">
    Create an array that can hold ten integers. Fill up each slot of the array with a random number from 1 to 100. Then display the contents of the array on the screen. You must use a loop.

    And, like last time, you must use the `length` field of your array and not a literal number (like 10) in the condition of the loop.

    **Sample Output**

    ```bash theme={null}
    Slot 0 contains a 45
    Slot 1 contains a 87
    Slot 2 contains a 39
    Slot 3 contains a 32
    Slot 4 contains a 93
    Slot 5 contains a 86
    Slot 6 contains a 12
    Slot 7 contains a 44
    Slot 8 contains a 75
    Slot 9 contains a 50
    ```
  </Tab>

  <Tab title="Answer">
    ```java BasicArrays2.java theme={null}
    import java.util.Random;
    public class BasicArrays2 {
        public static void main(String[] args) {
            Random r = new Random();
            int[] arr = new int[10];
            for (int i = 0; i < arr.length; i++) {
                arr[i] = 1 + r.nextInt(100);
                System.out.println("Slot " + i + " contains a " + arr[i]);
            }

        }
    }
    ```
  </Tab>
</Tabs>

## 141. Basic Arrays 3 - [Link](https://programmingbydoing.com/a/basic-arrays-3.html)

<Tabs>
  <Tab title="Task">
    Create an array that can hold 1000 integers. Fill the array with random numbers in the range 10-99. Then display the contents of the array on the screen. You must use a loop.

    If you're careful to only pick random numbers from 10 to 99 and you put two spaces after each number, then your output will line up like mine.

    And if you've forgotten how to pick random numbers in a certain range, you can check out my [random ranges visualizer](https://programmingbydoing.com/a/examples/RandomRanges2.html).

    **Sample Output**

    ```bash theme={null}
    81  69  34  39  35  19  68  14  93  91  96  90  67  82  15  75  13  34  39  88
    89  70  53  31  52  79  89  97  36  56  33  61  67  98  57  85  90  55  82  94
    50  91  96  73  60  58  56  46  64  71  79  54  40  79  24  68  21  37  55  33
    59  46  95  12  98  12  92  78  94  14  17  16  15  99  36  40  20  69  29  42
    88  50  31  60  65  57  79  53  30  84  28  97  66  23  88  97  18  86  44  79
    90  63  59  97  11  28  57  88  71  89  42  84  28  55  42  13  16  48  58  68
    49  92  53  25  26  25  31  53  91  50  73  80  21  86  87  60  63  59  44  39
    59  25  46  11  14  21  52  97  35  27  56  49  75  13  30  57  20  74  56  39
    35  46  20  62  21  59  87  43  81  24  75  42  79  26  40  19  92  50  57  32
    26  71  10  65  62  98  44  69  60  66  51  72  87  24  82  36  81  69  22  88
    68  73  28  49  74  15  19  44  11  11  73  55  23  73  30  94  85  92  11  53
    12  69  70  17  51  40  57  28  94  93  93  90  64  45  50  90  65  66  15  42
    97  69  48  96  15  11  29  19  90  73  76  33  19  14  37  20  15  69  47  58
    24  81  84  34  84  26  20  49  98  16  71  47  75  18  28  26  25  21  39  42
    17  58  40  10  29  17  55  35  18  59  20  88  49  42  74  65  75  52  41  93
    96  19  82  34  29  71  30  86  91  15  36  85  28  24  43  38  17  76  95  30
    31  48  15  96  47  56  67  70  87  16  42  96  21  20  75  70  68  11  21  50
    55  51  93  56  20  21  89  49  13  33  18  62  72  95  94  62  88  91  26  46
    81  28  70  87  43  30  54  82  54  39  68  54  22  99  61  29  77  19  74  87
    32  44  65  32  73  88  58  23  32  23  62  27  45  84  44  33  60  23  62  64
    59  90  20  49  33  11  48  90  39  49  64  54  21  52  66  61  18  65  97  59
    22  53  18  80  12  67  88  57  73  65  14  82  41  73  22  42  58  69  94  87
    11  35  64  81  34  30  41  16  99  42  74  96  92  47  62  49  31  34  24  99
    22  76  96  15  25  77  49  71  98  60  17  67  86  52  25  17  25  67  17  26
    53  42  40  46  10  36  33  67  15  79  48  69  57  91  29  36  50  71  39  10
    22  55  76  93  80  48  74  85  26  64  93  83  33  30  65  34  96  12  44  43
    36  13  64  59  23  70  87  73  87  12  96  65  83  79  23  92  56  86  39  57
    94  46  62  75  60  12  14  15  82  91  43  85  64  73  79  14  38  46  63  82
    17  49  56  22  64  10  84  67  66  85  78  22  72  53  33  18  43  90  94  61
    92  52  42  95  32  61  92  24  22  23  57  96  27  45  41  97  24  52  74  23
    28  52  94  64  24  47  62  48  46  72  27  50  15  37  10  75  66  53  42  81
    69  12  76  84  43  79  89  75  76  89  93  13  32  85  67  24  97  65  14  62
    10  47  25  62  73  40  71  66  11  81  22  33  22  90  55  39  26  63  14  45
    51  71  68  26  63  71  19  95  95  93  18  17  20  56  28  74  23  85  44  83
    54  99  77  57  97  14  13  54  44  35  27  55  29  58  41  35  26  23  64  53
    11  55  92  10  42  57  73  59  21  92  24  53  65  60  16  26  53  69  49  61
    66  87  34  15  19  85  33  96  16  11  57  11  19  38  86  55  21  12  19  21
    75  69  92  45  90  96  67  33  88  99  68  76  22  60  60  11  42  62  44  23
    65  74  15  92  47  35  83  79  71  86  44  86  68  97  60  66  14  75  45  56
    12  98  11  10  16  38  54  83  51  83  49  62  63  24  68  13  31  13  41  34
    59  35  12  88  12  21  55  93  27  92  27  14  39  58  31  39  25  94  83  88
    70  69  22  71  41  43  34  45  27  26  77  11  39  32  96  78  67  58  54  84
    19  26  96  14  29  92  11  28  68  91  93  74  53  13  84  99  70  11  91  70
    75  55  87  16  57  17  58  13  75  79  65  51  75  33  87  54  22  63  48  45
    71  79  12  40  52  71  62  38  77  36  88  53  94  88  58  20  28  11  48  59
    74  33  52  78  76  38  42  20  80  99  53  64  81  79  16  30  18  46  79  70
    43  83  14  71  99  64  84  94  20  54  74  40  37  22  96  34  83  85  11  99
    64  21  37  80  68  34  17  87  88  53  29  27  42  44  59  37  52  85  64  34
    93  23  35  13  46  14  59  87  42  78  52  89  14  52  37  30  74  22  70  79
    18  80  32  34  84  98  68  27  89  30  44  86  57  49  51  65  71  30  37  63
    ```
  </Tab>

  <Tab title="Answer">
    ```java BasicArrays3.java theme={null}
    import java.util.Random;
    public class BasicArrays3 {
        public static void main(String[] args) {
            Random r = new Random();
            int[] arr = new int[1000];
            for (int i = 0; i < arr.length; i++) {
                arr[i] = 10 + r.nextInt(90);
                System.out.print(arr[i] + "  ");
                if ((i + 1) % 20 == 0) {
                    System.out.println();
                }
            }
        }
    }
    ```
  </Tab>
</Tabs>

## 142. Copying Arrays - [Link](https://programmingbydoing.com/a/copying-arrays.html)

<Tabs>
  <Tab title="Task">
    Write a program that creates an array of ten integers. It should put ten random numbers from 1 to 100 in the array. It should copy all the elements of that array into another array of the same size. Then display the contents of both arrays. To get the output to look like mine, you'll need a several `for` loops.

    Create an array of ten integers

    * Fill the array with ten random numbers (1-100)
    * Copy the array into another array of the same capacity
    * Change the last value in the first array to a -7
    * Display the contents of both arrays

    **Sample Output**

    ```bash theme={null}
    Array 1: 45 87 39 32 93 86 12 44 75 -7
    Array 2: 45 87 39 32 93 86 12 44 75 50
    ```
  </Tab>

  <Tab title="Answer">
    ```java CopyingArrays.java theme={null}
    import java.util.Random;
    public class CopyingArrays {
        public static void main(String[] args) {
            Random r = new Random();
            int[] arr1 = new int[10];
            int[] arr2 = new int[10];
            for (int i = 0; i < arr1.length; i++) {
                arr1[i] = 1 + r.nextInt(100);
                arr2[i] = arr1[i];
            }
            arr1[arr1.length - 1] = -7;

            System.out.print("Array 1: ");
            for (int i = 0; i < arr1.length; i++) {
                System.out.print(arr1[i] + " ");
            }
            System.out.println();

            System.out.print("Array 2: ");
            for (int i = 0; i < arr2.length; i++) {
                System.out.print(arr2[i] + " ");
            }
        }
    }
    ```
  </Tab>
</Tabs>

## 143. Grades in an Array and a File - [Link](https://programmingbydoing.com/a/grades-in-an-array-and-a-file.html)

<Tabs>
  <Tab title="Task">
    Prompt the user for a first and last name, and the name for a file. Randomly choose five grades for that person from 1 to 100 and store them in an array that can hold five integers. Then output the first and last name and those five grades to the specified file.

    **Sample Output**

    ```bash theme={null}
    Name (first last): Marc Antony
    Filename: ettu.txt

    Here are your randomly-selected grades (hope you pass):
    Grade 1: 54
    Grade 2: 90
    Grade 3: 18
    Grade 4: 37
    Grade 5: 62

    Data saved in "ettu.txt".
    ```

    Later, if you look in "ettu.txt" (or whatever you called your file), you should see values like this:

    ```bash ettu.txt theme={null}
    Marc Antony
    54 90 18 37 62
    ```
  </Tab>

  <Tab title="Answer">
    ```java GradesInAnArrayAndAFile.java theme={null}
    import java.util.Random;
    import java.util.Scanner;
    import java.io.FileWriter;
    import java.io.File;

    public class GradesInAnArrayAndAFile {
        public static void main(String[] args) throws Exception {
            Scanner input = new Scanner(System.in);
            Random r = new Random();

            System.out.print("Name (first last): ");
            String firstName = input.next();
            String lastName = input.next();
            System.out.print("Filename: ");
            String filename = input.next();

            int[] grades = new int[5];
            for (int i = 0; i < grades.length; i++) {
                grades[i] = 1 + r.nextInt(100);
            }

            FileWriter fw = new FileWriter(new File(filename));
            fw.write(firstName + " " + lastName + "\n");
            for (int i = 0; i < grades.length; i++) {
                fw.write(grades[i] + " ");
            }
            fw.close();

            System.out.println("\nHere are your randomly-selected grades (hope you pass):");
            for (int i = 0; i < grades.length; i++) {
                System.out.println("Grade " + (i + 1) + ": " + grades[i]);
            }

            System.out.println("\nData saved in \"" + filename + "\".");
        }
    }
    ```
  </Tab>
</Tabs>

## 144. Finding a Value in an Array - [Link](https://programmingbydoing.com/a/finding-a-value-in-an-array.html)

<Tabs>
  <Tab title="Task">
    Create an array that can hold ten integers, and fill each slot with a different random value from 1-50. Display those values on the screen, and then prompt the user for an integer. Search through the array, and if the item is present, say so. It is not necessary to display anything if the value was not found. If the item is in the array multiple times, it's okay if the program prints the message more than once.

    **Sample Output**

    ```bash theme={null}
    Array: 45 39 32 12 44 50 26 42 16 20
    Value to find: 42

    42 is in the array.
    ```

    ```bash theme={null}
    Array: 45 39 32 12 44 50 26 42 16 20
    Value to find: 43
    ```

    ```bash theme={null}
    Array: 24 30 31 24 32 33 34 24 35 36
    Value to find: 24

    24 is in the array.
    24 is in the array.
    24 is in the array.
    ```
  </Tab>

  <Tab title="Answer">
    ```java FindingAValueInAnArray.java theme={null}
    import java.util.Random;
    import java.util.Scanner;

    public class FindingAValueInAnArray {
        public static void main(String[] args) {
            Random r = new Random();
            Scanner input = new Scanner(System.in);

            int[] arr = new int[10];
            for (int i = 0; i < arr.length; i++) {
                arr[i] = 1 + r.nextInt(50);
            }

            System.out.print("Array: ");
            for (int i = 0; i < arr.length; i++) {
                System.out.print(arr[i] + " ");
            }

            System.out.print("\nValue to find: ");
            int value = input.nextInt();

            for (int i = 0; i < arr.length; i++) {
                if (arr[i] == value) {
                    System.out.println("\n" + value + " is in the array.");
                }
            }
        }
    }
    ```
  </Tab>
</Tabs>

## 145. How Many Times? - [Link](https://programmingbydoing.com/a/how-many-times.html)

<Tabs>
  <Tab title="Task">
    Create an array that can hold ten integers, and fill each slot with a different random value from 1-50. Display those values on the screen, and then prompt the user for an integer. Search through the array, and count the number of times the item is found.

    **Sample Output**

    ```bash theme={null}
    Array: 45 39 32 12 44 50 26 42 16 20
    Value to find: 42

    42 was found 1 times.

    Array: 45 39 32 12 44 50 26 42 16 20
    Value to find: 43

    43 was found 0 times.

    Array: 24 30 31 24 32 33 34 24 35 36
    Value to find: 24

    24 was found 3 times.
    ```
  </Tab>

  <Tab title="Answer">
    ```java HowManyTimes.java theme={null}
    import java.util.Random;
    import java.util.Scanner;

    public class HowManyTimes {
        public static void main(String[] args) {
            Random r = new Random();
            Scanner input = new Scanner(System.in);

            int[] arr = new int[10];

            System.out.print("Array: ");
            for (int i = 0; i < arr.length; i++) {
                arr[i] = 1 + r.nextInt(50);
                System.out.print(arr[i] + " ");
            }

            System.out.print("\nValue to find: ");
            int value = input.nextInt();

            int count = 0;
            for (int i = 0; i < arr.length; i++) {
                if (arr[i] == value) {
                    count++;
                }
            }

            System.out.println("\n" + value + " was found " + count + " times.");
        }
    }
    ```
  </Tab>
</Tabs>

## 146. Is It There or Not? - [Link](https://programmingbydoing.com/a/is-it-there-or-not.html)

<Tabs>
  <Tab title="Task">
    Create an array that can hold ten integers, and fill each slot with a different random value from 1-50. Display those values on the screen, and then prompt the user for an integer. Search through the array, and if the item is present, say so. If the value is not in the array, display a single message saying so. Just like the previous assignment, if the value is present more than once, you may display the message as many times as necessary.

    **Sample Output**

    ```bash theme={null}
    Array: 45 39 32 12 44 50 26 42 16 20
    Value to find: 42

    42 is in the array.

    Array: 45 39 32 12 44 50 26 42 16 20
    Value to find: 43

    43 is not in the array.
    ```
  </Tab>

  <Tab title="Answer">
    ```java IsItThereOrNot.java theme={null}
    import java.util.Random;
    import java.util.Scanner;

    public class IsItThereOrNot {
        public static void main(String[] args) {
            Random r = new Random();
            Scanner input = new Scanner(System.in);

            int[] arr = new int[10];

            System.out.print("Array: ");
            for (int i = 0; i < arr.length; i++) {
                arr[i] = 1 + r.nextInt(50);
                System.out.print(arr[i] + " ");
            }

            System.out.print("\nValue to find: ");
            int value = input.nextInt();

            boolean found = false;
            for (int i = 0; i < arr.length; i++) {
                if (arr[i] == value) {
                    found = true;
                }
            }

            if (found) {
                System.out.println("\n" + value + " is in the array.");
            } else {
                System.out.println("\n" + value + " is not in the array.");
            }
        }
    }
    ```
  </Tab>
</Tabs>

## 147. Where Is It? - [Link](https://programmingbydoing.com/a/where-is-it.html)

<Tabs>
  <Tab title="Task">
    Create an array that can hold ten integers, and fill each slot with a different random value from 1-50. Display those values on the screen, and then prompt the user for an integer. Search through the array, and if the item is present, give the slot number where it is located. If the value is not in the array, display a single message saying so. If the value is present more than once, you may either display the message as many times as necessary, or display a single message giving the last slot number in which it appeared.

    **Sample Output**

    ```bash theme={null}
    Array: 45 39 32 12 44 50 42 26 16 20
    Value to find: 42

    42 is in slot 6.
    ```

    ```bash theme={null}
    Array: 45 39 32 12 44 50 26 42 16 20
    Value to find: 43

    43 is not in the array.
    ```

    ```bash theme={null}
    Array: 24 30 31 24 32 33 34 24 35 36
    Value to find: 24

        you may display either

    24 is in slot 0.
    24 is in slot 3.
    24 is in slot 7.

        or

    24 is in slot 7.
    ```
  </Tab>

  <Tab title="Answer">
    ```java WhereIsIt.java theme={null}
    import java.util.Random;
    import java.util.Scanner;

    public class WhereIsIt {
        public static void main(String[] args) {
            Random r = new Random();
            Scanner input = new Scanner(System.in);

            int[] arr = new int[10];

            System.out.print("Array: ");
            for (int i = 0; i < arr.length; i++) {
                arr[i] = 1 + r.nextInt(50);
                System.out.print(arr[i] + " ");
            }

            System.out.print("\nValue to find: ");
            int value = input.nextInt();

            boolean found = false;
            for (int i = 0; i < arr.length; i++) {
                if (arr[i] == value) {
                    System.out.println("\n" + value + " is in slot " + i + ".");
                    found = true;
                }
            }

            if (!found) {
                System.out.println("\n" + value + " is not in the array.");
            }
        }
    }
    ```
  </Tab>
</Tabs>

## 148. Finding the Largest Value in an Array - [Link](https://programmingbydoing.com/a/finding-the-largest-value-in-an-array.html)

<Tabs>
  <Tab title="Task">
    Write a program that creates an array which can hold ten values. Fill the array with random numbers from 1 to 100. Display the values in the array on the screen. Then use a linear search to find the largest value in the array, and display that value.

    **Sample Output**

    ```bash theme={null}
    Array: 45 87 39 32 93 86 12 44 75 50

    The largest value is 93
    ```
  </Tab>

  <Tab title="Answer">
    ```java FindingTheLargestValueInAnArray.java theme={null}
    import java.util.Random;

    public class FindingTheLargestValueInAnArray {
        public static void main(String[] args) {
            Random r = new Random();
            int[] arr = new int[10];
            int max = 0;

            System.out.print("Array: ");
            for (int i = 0; i < arr.length; i++) {
                arr[i] = 1 + r.nextInt(100);
                System.out.print(arr[i] + " ");
                if (arr[i] > max) {
                    max = arr[i];
                }
            }

            System.out.println("\n\nThe largest value is " + max);
        }
    }
    ```
  </Tab>
</Tabs>

## 149. Locating the Largest Value in an Array - [Link](https://programmingbydoing.com/a/locating-the-largest-value-in-an-array.html)

<Tabs>
  <Tab title="Task">
    Write a program that creates an array which can hold ten values. Fill the array with random numbers from 1 to 100. Display the values in the array on the screen. Then use a linear search to find the largest value in the array, and display that value and its slot number.

    **Sample Output**

    ```bash theme={null}
    Array: 45 87 39 32 93 86 12 44 75 50

    The largest value is 93
    It is in slot 4
    ```
  </Tab>

  <Tab title="Answer">
    ```java LocatingLargest.java theme={null}
    import java.util.Random;

    public class LocatingLargest {
        public static void main(String[] args) {
            Random r = new Random();
            int[] arr = new int[10];
            int max = 0;
            int slot = 0;

            System.out.print("Array: ");
            for (int i = 0; i < arr.length; i++) {
                arr[i] = 1 + r.nextInt(100);
                System.out.print(arr[i] + " ");
                if (arr[i] > max) {
                    max = arr[i];
                    slot = i;
                }
            }

            System.out.println("\n\nThe largest value is " + max);
            System.out.println("It is in slot " + slot);
        }
    }
    ```
  </Tab>
</Tabs>

## 150. Giving an Array a Bunch of Values at Once - [Link](https://programmingbydoing.com/a/giving-an-array-a-bunch-of-values-at-once.html)

<Tabs>
  <Tab title="Task">
    Write a program that creates an array which can hold ten values. Fill the array with random numbers from 1 to 100. Display the values in the array on the screen. Then use a linear search to find the largest value in the array, and display that value and its slot number.

    **Files Needed**

    * [GivingAnArrayABunchOfValuesAtOnce.java](https://programmingbydoing.com/a/examples/GivingAnArrayABunchOfValuesAtOnce.java)

    **Sample Output**

    ```bash theme={null}
    The first array is filled with the following values:
        alpha bravo charlie
    ```

    After you add in the code you're supposed to, you should see something more like this:

    ```bash theme={null}
    The first array is filled with the following values:
        alpha bravo charlie delta echo
    The second array is filled with the following values:
        11 23 37 41 53
    ```
  </Tab>

  <Tab title="Answer">
    ```java GivingAnArrayABunchOfValuesAtOnce.java theme={null}
    public class GivingAnArrayABunchOfValuesAtOnce {
        public static void main(String[] args) {
            String[] arr1 = {"alpha", "bravo", "charlie", "delta", "echo"};
            int[] arr2 = {11, 23, 37, 41, 53};

            System.out.println("The first array is filled with the following values:");
            for (int i = 0; i < arr1.length; i++) {
                System.out.print("    " + arr1[i]);
            }

            System.out.println("\nThe second array is filled with the following values:");
            for (int i = 0; i < arr2.length; i++) {
                System.out.print("    " + arr2[i]);
            }
        }
    }
    ```
  </Tab>
</Tabs>

## 151. Parallel Arrays - [Link](https://programmingbydoing.com/a/parallel-arrays.html)

<Tabs>
  <Tab title="Task">
    Create three arrays to store data about five people. The first array should be `Strings` and should hold their last names. The next array should be `doubles` and should hold a grade average (on a 100-point scale). The last array should be `ints`, should hold their student id numbers.

    Give each of the arrays values (using [array initializers](https://programmingbydoing.com/a/giving-an-array-a-bunch-of-values-at-once.html)). Then print the values of all three arrays on the screen.

    Finally, ask the user for an ID number to lookup. Search through the ID array until you find that ID, and then print out the values from the same slot number of the other two arrays.

    **Sample Output**

    ```bash theme={null}
    Values:
        Mitchell 99.5 123456
        Ortiz 78.5 813225
        Luu 95.6 823669
        Zimmerman 96.8 307760
        Brooks 82.7 827131

    ID number to find: 307760

    Found in slot 3
        Name: Zimmerman
        Average: 96.8
        ID: 307760
    ```
  </Tab>

  <Tab title="Answer">
    ```java ParallelArrays.java theme={null}
    import java.util.Scanner;

    public class ParallelArrays {
        public static void main(String[] args) {
            String[] names = {"Mitchell", "Ortiz", "Luu", "Zimmerman", "Brooks"};
            double[] grades = {99.5, 78.5, 95.6, 96.8, 82.7};
            int[] ids = {123456, 813225, 823669, 307760, 827131};

            System.out.println("Values:");
            for (int i = 0; i < names.length; i++) {
                System.out.println("\t" + names[i] + " " + grades[i] + " " + ids[i]);
            }

            Scanner input = new Scanner(System.in);
            System.out.print("\nID number to find: ");
            int id = input.nextInt();

            for (int i = 0; i < ids.length; i++) {
                if (ids[i] == id) {
                    System.out.println("\nFound in slot " + i);
                    System.out.println("\tName: " + names[i]);
                    System.out.println("\tAverage: " + grades[i]);
                    System.out.println("\tID: " + ids[i]);
                }
            }
        }
    }
    ```
  </Tab>
</Tabs>

## 152. Tic-Tac-Toe - [Link](https://programmingbydoing.com/a/tic-tac-toe.html)

<Tabs>
  <Tab title="Task">
    Code an interactive, two-player game of Tic-Tac-Toe. You'll use a two-dimensional array of **chars**.

    **Starter Code**

    * [TicTacToe.java](https://programmingbydoing.com/a/examples/TicTacToe.java)

    **Sample Output**

    ```bash theme={null}
    (...a game already in progress)

        X   O
        O X X
        X O

    'O', choose your location (row, column): 0 1

        X O O
        O X X
        X O

    'X', choose your location (row, column): 2 0

        X O O
        O X X
        X X O

    The game is a tie.
    ```
  </Tab>

  <Tab title="Answer">
    ```java TicTacToe.java theme={null}
    import java.util.Scanner;

    public class TicTacToe
    {
        private static char[][] board = new char[3][3];

        public static void main( String[] args )
        {
            Scanner keyboard = new Scanner(System.in);
            initBoard();
            displayBoard();

            char player = 'X';
            int turns = 0, row, col;
            while (true)
            {
                turns++;
                System.out.print( "\n'" + player + "', choose your location (row, column): " );
                row = keyboard.nextInt();
                col = keyboard.nextInt();

                if ( board[row][col] == ' ' )
                {
                    board[row][col] = player;
                }
                else
                {
                    System.out.println("That slot is already taken.");
                    continue;
                }

                displayBoard();
                if ( checkWinner(player) )
                {
                    System.out.println("Player " + player + " wins!");
                    break;
                }
                if ( turns == 9 )
                {
                    System.out.println("The game is a tie.");
                    break;
                }

                if ( player == 'X' )
                    player = 'O';
                else
                    player = 'X';
            }

        }

        public static void initBoard()
        {
            // fills up the board with blanks
            for ( int r=0; r<3; r++ )
                for ( int c=0; c<3; c++ )
                    board[r][c] = ' ';
        }

        public static void displayBoard()
        {
            System.out.println("  0  " + board[0][0] + "|" + board[0][1] + "|" + board[0][2]);
            System.out.println("    --+-+--");
            System.out.println("  1  " + board[1][0] + "|" + board[1][1] + "|" + board[1][2]);
            System.out.println("    --+-+--");
            System.out.println("  2  " + board[2][0] + "|" + board[2][1] + "|" + board[2][2]);
            System.out.println("     0 1 2 ");
        }

        public static void displayBoard2()
        {
            for ( int r=0; r<3; r++ )
            {
                System.out.print("\t"+r+" ");
                for ( int c=0; c<3; c++ )
                {
                    System.out.print( board[r][c] + " " );
                }
                System.out.println();
            }
            System.out.println("\t  0 1 2 ");
        }

        public static boolean checkWinner(char player)
        {
            for ( int i=0; i<3; i++ )
            {
                if ( board[i][0] == player && board[i][1] == player && board[i][2] == player )
                    return true;
                if ( board[0][i] == player && board[1][i] == player && board[2][i] == player )
                    return true;
            }
            if ( board[0][0] == player && board[1][1] == player && board[2][2] == player )
                return true;
            if ( board[0][2] == player && board[1][1] == player && board[2][0] == player )
                return true;

            return false;
        }
    }
    ```
  </Tab>
</Tabs>

## 153. Hangman - [Link](https://programmingbydoing.com/a/hangman.html)

<Tabs>
  <Tab title="Task">
    Write a program to play a word-guessing game like Hangman.

    * It must randomly choose a word from a list of words.
    * It must stop when all the letters are guessed.
    * It must give them limited tries and stop after they run out.
    * It must display letters they have already guessed (either only the incorrect guesses or all guesses).

    **Sample Output**

    ```bash theme={null}
    -=-=-=-=-=-=-=-=-=-=-=-=-=-

    Word:	_ _ _ _ _ _ _ _ _

    Misses:

    Guess:	e

    -=-=-=-=-=-=-=-=-=-=-=-=-=-

    Word:	_ e _ _ _ _ _ _ _

    Misses:

    Guess:	i

    -=-=-=-=-=-=-=-=-=-=-=-=-=-

    Word:	_ e _ i _ _ _ _ _

    Misses:

    Guess:	a

    -=-=-=-=-=-=-=-=-=-=-=-=-=-

    Word:	_ e _ i a _ _ a _

    Misses:

    Guess:	r

    -=-=-=-=-=-=-=-=-=-=-=-=-=-

    Word:	_ e _ i a _ _ a _

    Misses:	r

    Guess:	s

    -=-=-=-=-=-=-=-=-=-=-=-=-=-

    Word:	_ e _ i a _ _ a _

    Misses:	rs

    Guess:	t

    -=-=-=-=-=-=-=-=-=-=-=-=-=-

    Word:	_ e _ i a t _ a _

    Misses:	rs

    Guess:	n

    -=-=-=-=-=-=-=-=-=-=-=-=-=-

    Word:	_ e _ i a t _ a n

    Misses:	rs

    Guess:	o

    -=-=-=-=-=-=-=-=-=-=-=-=-=-

    Word:	_ e _ i a t _ a n

    Misses:	rso

    Guess:	l

    -=-=-=-=-=-=-=-=-=-=-=-=-=-

    Word:	l e _ i a t _ a n

    Misses:	rso

    Guess:	v

    -=-=-=-=-=-=-=-=-=-=-=-=-=-

    Word:	l e v i a t _ a n

    Misses:	rso

    Guess:	h

    -=-=-=-=-=-=-=-=-=-=-=-=-=-

    Word:	l e v i a t h a n

    Misses:	rso

    YOU GOT IT!

    Play "again" or "quit"? quit
    ```
  </Tab>

  <Tab title="Answer">
    ```java Hangman.java theme={null}
    import java.util.Scanner;
    import java.util.Random;

    public class Hangman {
        public static void main(String[] args) {
            Scanner input = new Scanner(System.in);
            Random r = new Random();

            String[] words = {"leviathan", "gargantuan", "behemoth", "kraken", "hydra"};
            String word = words[r.nextInt(words.length)];
            String guess = "";
            String misses = "";
            int tries = 7;

            System.out.println("Welcome to Hangman!");
            while (true) {
                System.out.println("\n=-=-=-=-=-=-=-=-=-=-=-=-");
                System.out.println("\nWord: " + displayWord(word, guess));
                System.out.println("\nMisses: " + misses);
                System.out.print("\nGuess: ");
                char letter = input.next().charAt(0);

                if (word.contains(String.valueOf(letter))) {
                    guess += letter;
                } else {
                    misses += letter;
                    tries--;
                }

                if (word.equals(displayWord(word, guess).replace(" ", ""))) {
                    System.out.println("\n=-=-=-=-=-=-=-=-=-=-=-=-");
                    System.out.println("\nWord: " + displayWord(word, guess));
                    System.out.println("\nMisses: " + misses);
                    System.out.println("\nYOU GOT IT!");
                    break;
                }

                if (tries == 0) {
                    System.out.println("\nYou ran out of tries!");
                    break;
                }
            }

            System.out.print("\nPlay \"again\" or \"quit\"? ");
            String choice = input.next();
            if (choice.equals("again")) {
                main(null);
            }
        }

        public static String displayWord(String word, String guess) {
            String result = "";
            for (int i = 0; i < word.length(); i++) {
                if (guess.contains(String.valueOf(word.charAt(i)))) {
                    result += word.charAt(i);
                } else {
                    result += "_";
                }
                result += " ";
            }
            return result;
        }
    }
    ```
  </Tab>
</Tabs>