06.02.2025

src/de/dhbwka/java/exercise/arrays/BubbleSort.java

@@ -0,0 +1,32 @@
+package de.dhbwka.java.exercise.arrays;
+
+public class BubbleSort {
+  public static void main(String[] args) {
+    java.util.Scanner scan = new java.util.Scanner(System.in);
+    System.out.print("Anzahl der Elemente: ");
+    int n = scan.nextInt();
+
+    int[] arr = new int[n];
+    for (int i = 0; i < n; i++) {
+      System.out.print("Element " + i + ": ");
+      arr[i] = scan.nextInt();
+    }
+
+    scan.close();
+
+    for (int i = 0; i < arr.length; i++) {
+      for (int j = 0; j < arr.length - 1; j++) {
+        if (arr[j] > arr[j + 1]) {
+          int temp = arr[j];
+          arr[j] = arr[j + 1];
+          arr[j + 1] = temp;
+        }
+      }
+    }
+
+    for (int i : arr) {
+      System.out.print(i + " ");
+    }
+    System.out.println();
+  }
+}

src/de/dhbwka/java/exercise/arrays/DotProduct.java

@@ -0,0 +1,26 @@
+package de.dhbwka.java.exercise.arrays;
+
+public class DotProduct {
+  public static void main(String[] args) {
+    java.util.Scanner scan = new java.util.Scanner(System.in);
+    System.out.print("Anzahl der Elemente: ");
+    int n = scan.nextInt();
+    double[] arr1 = new double[n];
+    double[] arr2 = new double[n];
+    for (int i = 0; i < n; i++) {
+      System.out.print("Element " + i + " (Array 1): ");
+      arr1[i] = scan.nextDouble();
+    }
+    for (int i = 0; i < n; i++) {
+      System.out.print("Element " + i + " (Array 2): ");
+      arr2[i] = scan.nextDouble();
+    }
+    scan.close();
+
+    double dotProduct = 0;
+    for (int i = 0; i < n; i++) {
+      dotProduct += arr1[i] * arr2[i];
+    }
+    System.out.println("Skalarprodukt: " + dotProduct);
+  }
+}

src/de/dhbwka/java/exercise/arrays/Eratostenes.java

@@ -0,0 +1,54 @@
+package de.dhbwka.java.exercise.arrays;
+
+public class Eratostenes {
+  private static final int NUM = 1000;
+
+  public static void main(String[] args) {
+    // List<Integer> sieve = new java.util.ArrayList<>();
+    // List<Integer> primes = new java.util.ArrayList<>();
+
+    // for (int i = 2; i <= NUM; i++) {
+    // sieve.add(i);
+    // }
+
+    // while (!sieve.isEmpty()) {
+    // int prime = sieve.get(0);
+    // primes.add(prime);
+    // sieve.removeIf(i -> i % prime == 0);
+    // }
+
+    // System.out.println(primes);
+
+    boolean[] sieve = new boolean[NUM + 1];
+    for (int i = 2; i < sieve.length; i++) {
+      sieve[i] = true;
+    }
+    boolean[] primes = new boolean[NUM + 1];
+
+    while (true) {
+      int prime = -1;
+      for (int i = 2; i < sieve.length; i++) {
+        if (sieve[i]) {
+          prime = i;
+          break;
+        }
+      }
+
+      if (prime == -1) {
+        break;
+      }
+
+      primes[prime] = true;
+
+      for (int i = prime; i < sieve.length; i += prime) {
+        sieve[i] = false;
+      }
+    }
+
+    for (int i = 2; i < primes.length; i++) {
+      if (primes[i]) {
+        System.out.println(i);
+      }
+    }
+  }
+}

src/de/dhbwka/java/exercise/arrays/Fibonacci.java

@@ -0,0 +1,18 @@
+package de.dhbwka.java.exercise.arrays;
+
+public class Fibonacci {
+  private static final int NUM = 50;
+
+  public static void main(String[] args) {
+    long[] lastTwo = { 0, 1 };
+    System.out.println(lastTwo[0]);
+    System.out.println(lastTwo[1]);
+
+    for (int i = 2; i < NUM; i++) {
+      long next = lastTwo[0] + lastTwo[1];
+      System.out.println(next);
+      lastTwo[0] = lastTwo[1];
+      lastTwo[1] = next;
+    }
+  }
+}

src/de/dhbwka/java/exercise/arrays/MatrixSubtraction.java

@@ -0,0 +1,54 @@
+package de.dhbwka.java.exercise.arrays;
+
+public class MatrixSubtraction {
+  private static int[][] generateRandomMatrix(int x, int y, int max) {
+    int[][] matrix = new int[x][y];
+    for (int i = 0; i < x; i++) {
+      for (int j = 0; j < y; j++) {
+        matrix[i][j] = (int) (Math.random() * max);
+      }
+    }
+    return matrix;
+  }
+
+  private static int[][] subtractMatrix(int[][] matrix1, int[][] matrix2) {
+    int[][] result = new int[matrix1.length][matrix1[0].length];
+    for (int i = 0; i < matrix1.length; i++) {
+      for (int j = 0; j < matrix1[0].length; j++) {
+        result[i][j] = matrix1[i][j] - matrix2[i][j];
+      }
+    }
+    return result;
+  }
+
+  public static void main(String[] args) {
+    int[][] matrix1 = generateRandomMatrix(3, 4, 100);
+    int[][] matrix2 = generateRandomMatrix(3, 4, 100);
+
+    System.out.println("Matrix 1:");
+    for (int i = 0; i < matrix1.length; i++) {
+      for (int j = 0; j < matrix1[0].length; j++) {
+        System.out.printf("%3d ", matrix1[i][j]);
+      }
+      System.out.println();
+    }
+
+    System.out.println("Matrix 2:");
+    for (int i = 0; i < matrix2.length; i++) {
+      for (int j = 0; j < matrix2[0].length; j++) {
+        System.out.printf("%3d ", matrix2[i][j]);
+      }
+      System.out.println();
+    }
+
+    int[][] result = subtractMatrix(matrix1, matrix2);
+
+    System.out.println("Result:");
+    for (int i = 0; i < result.length; i++) {
+      for (int j = 0; j < result[0].length; j++) {
+        System.out.printf("%3d ", result[i][j]);
+      }
+      System.out.println();
+    }
+  }
+}

src/de/dhbwka/java/exercise/arrays/Norm.java

@@ -0,0 +1,21 @@
+package de.dhbwka.java.exercise.arrays;
+
+public class Norm {
+  public static void main(String[] args) {
+    java.util.Scanner scan = new java.util.Scanner(System.in);
+    System.out.print("Anzahl der Elemente: ");
+    int n = scan.nextInt();
+    double[] arr = new double[n];
+    for (int i = 0; i < n; i++) {
+      System.out.print("Element " + i + ": ");
+      arr[i] = scan.nextDouble();
+    }
+    scan.close();
+
+    double sum = 0;
+    for (double d : arr) {
+      sum += d * d;
+    }
+    System.out.println("Norm: " + Math.sqrt(sum));
+  }
+}

src/de/dhbwka/java/exercise/arrays/Pascal.java

@@ -0,0 +1,27 @@
+package de.dhbwka.java.exercise.arrays;
+
+public class Pascal {
+  private static final int SIZE = 9;
+
+  public static void main(String[] args) {
+    int[][] pascal = new int[SIZE][];
+    for (int i = 0; i < SIZE; i++) {
+      pascal[i] = new int[i + 1];
+      pascal[i][0] = 1;
+      pascal[i][i] = 1;
+      for (int j = 1; j < i; j++) {
+        pascal[i][j] = pascal[i - 1][j - 1] + pascal[i - 1][j];
+      }
+    }
+
+    for (int i = 0; i < SIZE; i++) {
+      for (int j = 0; j < SIZE - i; j++) {
+        System.out.print("   ");
+      }
+      for (int j = 0; j < pascal[i].length; j++) {
+        System.out.printf("%6d", pascal[i][j]);
+      }
+      System.out.println();
+    }
+  }
+}

src/de/dhbwka/java/exercise/arrays/StandardDeviation.java

@@ -0,0 +1,22 @@
+package de.dhbwka.java.exercise.arrays;
+
+import java.util.Arrays;
+
+public class StandardDeviation {
+  private static double stdDev(int[] arr) {
+    return Math.sqrt(Arrays.stream(arr).mapToDouble(i -> Math.pow(i - average(arr), 2)).sum() / (arr.length - 1));
+  }
+
+  private static double average(int[] arr) {
+    return Arrays.stream(arr).sum() / arr.length;
+  }
+
+  public static void main(String[] args) {
+    int[] arr = new int[100];
+    for (int i = 0; i < arr.length; i++) {
+      arr[i] = (int) (Math.random() * 100);
+    }
+    System.out.println("Standardabweichung: " + stdDev(arr));
+    System.out.println("Mittelwert: " + average(arr));
+  }
+}