1-20 + Extra Exercises CS106

exercises.java

package tester;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;

public class Test {

    public static void main(String[] args) {
        rollingDice();
    }

    private static void exercise1() {
        for (int iterator = 5; iterator <= 99; ++iterator) {
            if (iterator % 2 != 0) {
                System.out.println(iterator);
            }
        }
    }

    private static void exercise2() {
        for (float celsius = -40; celsius <= 40; celsius+=0.5) {
            float fahrenheit = ((9 * celsius) / 5) + 32;
            System.out.println(celsius + "C in Fahrenheit is: " + fahrenheit + "F");
        }
    }

    public static void exercise3() {
        int sum = 0;
        for (int i = 1; i <= 100; ++i) {
            sum += i;
        }
        System.out.println("Sum: " + sum);
    }

    public static void exercise4() {
        int product = 1;
        for (int i = 1; i <= 21; i+=2) {
            product = product * i;
        }
        System.out.println(product);
    }

    public static void exercise5() {
        int sum = 0, var = 5;
        while (true) {
            sum += Math.pow(var, 2);
            var += 5;

            if (sum > 10000) {
                sum -= Math.pow(var, 2);
                break;
            }
        }
        System.out.println(sum);
    }

    public static void exercise6() {
        double[] heights = { 1.81, 2.01, 1.93, 1.92, 1.99, 1.93, 1.95, 1.60, 1.99, 2.00 };
        OptionalDouble d = Arrays.stream(heights).average();
        if (d.isPresent()) {
            System.out.println(d.getAsDouble());
        }
    }

    public static void exercise7() {
        try (
                BufferedReader reader = new BufferedReader(
                        new InputStreamReader(System.in)
                )
        ) {
            int max = 0, aStudents = 0;
            for (int index = 0; index < 8; ++index) {
                int grade = Integer.parseInt(reader.readLine());

                if (grade < 0 || grade > 100) {
                    throw new IllegalArgumentException("Grade should be between 0 and 100. (inclusive)");
                }

                if (grade >= 90) {
                    aStudents++;
                }

                if (grade > max) {
                    max = grade;
                }
            }

            System.out.println("The highest grade is " + max + " and the number of students that have received an A is " + aStudents);
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

    public static void exercise8() {
        try (
                BufferedReader reader = new BufferedReader(
                        new InputStreamReader(System.in)
                )
        ) {
            int max = Integer.MIN_VALUE; int min = Integer.MAX_VALUE, inputs = 0;

            while (true) {
                int a = Integer.parseInt(reader.readLine());
                if (a == 0) {
                    break;
                }

                if (a > max) {
                    max = a;
                }

                if (a < min) {
                    min = a;
                }

                ++inputs;
            }
            System.out.println(max + "\n" + min + "\n" + inputs + "\n");
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

    public static void exercise9() {
        try (
                BufferedReader reader = new BufferedReader(
                        new InputStreamReader(System.in)
                )
        ) {

            int sum = 0, count = 0;
            while (true) {
                int a = Integer.parseInt(reader.readLine());
                sum += a;

                if (sum > 2000) {
                    break;
                }
                ++count;
            }
            System.out.println("Average: " + sum / count);
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

    public static void exercise10() {
        int population = 10000000;
        for (int year = 1; year <= 15; ++year) {
            population *= 1.02;
        }
        System.out.println(population);
    }

    public static void exercise11() {
        try (
                BufferedReader reader = new BufferedReader(
                        new InputStreamReader(System.in)
                )
        ) {
            int year = Integer.parseInt(reader.readLine());
            int days = 0;

            for (int index = year; index < 2020; ++index) {
                if (index % 4 == 0) {
                    days += 366;
                } else {
                    days += 365;
                }
            }

            System.out.println(days);
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

    public static void exercise12() {
        int row=32;
        int totalseats=800;

        for (int i=0; i<row; ++i)
        {
            totalseats=totalseats+100;
        }

        System.out.println("The number of total seats are: "+totalseats);
    }

    public static void exercise13() throws IOException // Declares that an error (exception) may occur
    {

        int cost = 200, budget = 47000, sum = 0, depth = 0;
        while (sum < 47000)
        {
            sum = sum + cost;
            if(sum > 47000)
            {
                break;
            }
            cost = cost + 50;
            depth++;
        }
        System.out.println("the maximal depth the farmer can afford is: " + depth + " meters" );
    }

    public static void exercise14() {
        Scanner sc = new Scanner(System.in);
        System.out.println("enter an integer");
        int a = sc.nextInt();

        System.out.println("");

        System.out.println("enter another integer");
        int b = sc.nextInt();
        int count_for12 = 0;

        while(a < b)
        {
            if(a % 12 == 0)
            {
                count_for12  = count_for12 + 1;
            }


            a = a+1;
        }

        System.out.println( "there are " + count_for12 + " multiples of 3 and 4" );
    }

    public static void exercise15() throws IOException // Declares that an error (exception) may occur
    {
        int a = 0;
        int count = 0;
        while(a < 1000)
        {
            if(a % 2 == 0 && a % 3 == 0 && a % 4 != 0)
            {
                System.out.println(a);
                count = count+1;
            }
            a = a+1;
        }
        System.out.println("there are: " + count + " numbers divisible by 2 and 3 but not by 4" );
    }

    public static void exercise16() {
        try (
                BufferedReader reader = new BufferedReader(
                        new InputStreamReader(System.in)
                )
        ) {
            int evens = 0, odds = 0;

            while (true) {
                int input = Integer.parseInt(reader.readLine());

                if (input < 1) {
                    throw new IllegalArgumentException();
                }

                if (input % 2 == 0) {
                    ++evens;
                } else {
                    ++odds;
                }

                if (evens == 400) {
                    System.out.println("Evens!");
                    break;
                }

                if (odds == 400) {
                    System.out.println("Odds!");
                    break;
                }
            }

        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

    public static void exercise17() {
        try (
                BufferedReader reader = new BufferedReader(
                        new InputStreamReader(System.in)
                )
        ) {
            int input, numbers = 5, sum = 0;

            for (int index = 0; index < 5; ++index) {
                input = Integer.parseInt(reader.readLine());
                sum += input;
            }

            while (sum < 1000) {
                input = Integer.parseInt(reader.readLine());
                sum += input;
                ++numbers;
            }

            System.out.println("Numbers that were entered: " + numbers);
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

    public static void exercise18() {
        int[] integerArray = new int[10];
        integerArray[0] = 3;

        for (int index = 1; index < integerArray.length; ++index) {
            integerArray[index] = integerArray[index - 1] * index;
        }
    }

    public static void exercise19() throws IOException {
        InputStreamReader isr = new InputStreamReader(System.in); // Variable (object) reading the keystrokes
        BufferedReader br = new BufferedReader(isr); // Variable (object) translating the input stream
        String inData = null; // Text variable to receive the user's input

        int[] elements = new int[5];

        for (int i = 0; i < 5; i++) {
            System.out.println("Enter a number: ");
            inData = br.readLine();
            elements[i] = Integer.parseInt(inData);
        }

        for (int i = elements.length - 1; i >= 0; i--) {
            System.out.println(2 * elements[i]);
        }
    }

    public static void exercise20v1() {
        Scanner input = new Scanner(System.in);
        int[] ID = new int[10];
        int[] grade = new int[10];
        int average, sum = 0;

        System.out.println("\tPlease enter your ID and your Grade:");

        for (int i = 0; i < 10; i++) {
            System.out.println("\tPlease enter your ID");

            while (!input.hasNextInt())
            {
                System.out.print("\tPlease enter an integer!.\n");
                String var9 = input.next();
            }

            ID[i] = input.nextInt();

            if (ID[i]< 0 || ID[i] > 30)
            {
                System.out.println("Please enter a valid ID");
                while(ID[i]< 0 || ID[i] > 30)
                {
                    System.out.println("Please enter a valid ID");
                    ID[i] = input.nextInt();
                }
            }

            System.out.println("\tPlease enter your Grade:");

            while (!input.hasNextInt()) {
                System.out.print("\tPlease enter an integer!.\n");
                String var9 = input.next();
            }

            grade[i] = input.nextInt();

            if (grade[i] < 0 || grade[i]> 100)
            {
                System.out.println("Please enter a valid grade.");
                while(grade[i] < 0 || grade[i]> 100)
                {
                    System.out.println("Please enter a valid grade.");
                    grade[i] = input.nextInt();
                }

            }

            sum = sum + grade[i];

        }
        average = sum / 10;

        for(int i=0; i< grade.length; ++i)
        {
            if (grade[i]>average)
                System.out.println("The student with ID "+ ID[i]+ " has a grade "+ grade [i]+ " over the average of the class of "+ average+".");

        }
    }

    public static void exercise20v2() {
        Map<Integer, Float> map = new HashMap<>();
        Random random = new Random();
        int id;
        float average, input, gradeSum = 0;

        try (
                BufferedReader reader = new BufferedReader(
                        new InputStreamReader(System.in)
                )
        ) {
            for (int index = 0; index < 10; ++index) {
                id = random.nextInt(31) + 1;
                input = Float.parseFloat(reader.readLine());
                gradeSum += input;
                map.put(id, input);
            }

            average = gradeSum / 10;

            for (Map.Entry<Integer, Float> entry : map.entrySet()) {
                if (entry.getValue() > average) {
                    System.out.println(entry.getKey());
                }
            }
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

    public static void rollingDice() {
        Random random = new Random();
        int[] frequencies = {0, 0, 0, 0, 0, 0};
        int[] doubleFrequencies = {0, 0, 0, 0, 0, 0};
        int[] sums = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};

        try (
                BufferedReader reader = new BufferedReader(
                        new InputStreamReader(System.in)
                )
        ) {
            int numberOfDiceThrows = Integer.parseInt(reader.readLine());

            for (int index = 0; index < numberOfDiceThrows; ++index) {
                int die1 = random.nextInt(6) + 1;
                int die2 = random.nextInt(6) + 1;

                ++frequencies[die1 - 1];
                ++frequencies[die2 - 1];
                ++sums[die1 + die2 - 2];

                if (die1 == die2) {
                    ++doubleFrequencies[die1 - 1];
                }
            }

            System.out.println("---------- Statistics ----------");
            System.out.println("---------- Number Frequencies ----------");
            for (int index = 1; index <= 6; ++index) {
                System.out.println("Frequency of [" + index + "]: " + frequencies[index - 1]);
                System.out.println("Fraction of roll: " + (frequencies[index - 1] / (float) Arrays.stream(frequencies).sum()) * 100 + "%");
            }
            System.out.println("---------- Double Frequencies ----------");
            for (int index = 1; index <= 6; ++index) {
                System.out.println("Frequency of double roll [" + index + "]: " + doubleFrequencies[index - 1]);
                System.out.println("Fraction of roll: " + (doubleFrequencies[index - 1] / (float) Arrays.stream(doubleFrequencies).sum()) * 100 + "%");
            }
            System.out.println("---------- Sum Frequencies ----------");
            for (int index = 2; index <= 12; ++index) {
                System.out.println("Frequency of sum [" + index + "]: " + sums[index - 2]);
                System.out.println("Fraction of sum: " + (sums[index - 2] / (float) Arrays.stream(sums).sum()) * 100 + "%");
            }

        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }
}