Sem I (Program I) - Practice

Question 1

Schreib ein Beispiel für Fakultätsberechnung(Factorial) mit Methode nutzung iterativ

Answer 1

class HelloWorld{
    public static int fakultaet(int eingabe) {
        int f = 1;
        for (int i = 2; i <= eingabe; i++)
            f = f * i;
        return f;
    }
    public static void main(String[] args) {
        int erg = fakultaet(5);
        System.out.println(erg);
    }
}

Question 2

Schreib ein Beispiel für Fakultätsberechnung(Factorial) ohne Methode nutzung

Answer 2

class HelloWorld{
    public static void main(String[] args) {
        int eingabe = 3;
        int f = 1;
        for (int i = 2; i <= eingabe; i++)
            f = f * i;
        System.out.print(f);
    }
}

Question 3

Schreib ein Beispiel für Fakultätsberechnung(Factorial) mit Methode nutzung und rekursion

Answer 3

class HelloWorld{
    public static int fakultaet(int eingabe) {
        if (eingabe <= 1)
            return 1;
        else
            return eingabe * fakultaet(eingabe - 1);
    }

    public static void main(String[] args) {
        int erg = fakultaet(5);
        System.out.println(erg);
    }
}

Question 4

Напиши пример алгоритма Bubble Sort

Answer 4

public class BubbleSort {
    public static void bubbleSort(int[] arr) {
        int n = arr.length;
        for (int i = 0; i < n-1; i++) {
            for (int j = 0; j < n-i-1; j++) {
                if (arr[j] > arr[j+1]) {
                    // Меняем arr[j] и arr[j+1] местами
                    int temp = arr[j];
                    arr[j] = arr[j+1];
                    arr[j+1] = temp;
                }
            }
        }
    }

Question 5

Напиши пример алгоритма Selection Sort

Answer 5

public class SelectionSort {
    public static void selectionSort(int[] arr) {
        int n = arr.length;
        for (int i = 0; i < n-1; i++) {
            int min_idx = i;
            for (int j = i+1; j < n; j++) {
                if (arr[j] < arr[min_idx]) {
                    min_idx = j;
                }
            }
            int temp = arr[min_idx];
            arr[min_idx] = arr[i];
            arr[i] = temp;
        }
    }

Question 6

Напиши пример алгоритма Insertion Sort

Answer 6

public class InsertionSort {
    public static void insertionSort(int[] arr) {
        int n = arr.length;
        for (int i = 1; i < n; ++i) {
            int key = arr[i];
            int j = i - 1;
            while (j >= 0 && arr[j] > key) {
                arr[j + 1] = arr[j];
                j = j - 1;
            }
            arr[j + 1] = key;
        }
    }

Question 7

Напиши пример алгоритма Merge Sort

Answer 7

public class MergeSort {
    public static void mergeSort(int[] arr, int l, int r) {
        if (l < r) {
            int m = l + (r - l) / 2;
            mergeSort(arr, l, m);
            mergeSort(arr, m + 1, r);
            merge(arr, l, m, r);
        }
    }
​
    public static void merge(int[] arr, int l, int m, int r) {
        int n1 = m - l + 1;
        int n2 = r - m;
        int[] L = new int[n1];
        int[] R = new int[n2];
​
        System.arraycopy(arr, l, L, 0, n1);
        System.arraycopy(arr, m + 1, R, 0, n2);
​
        int i = 0, j = 0, k = l;
        while (i < n1 && j < n2) {
            if (L[i] <= R[j]) {
                arr[k] = L[i];
                i++;
            } else {
                arr[k] = R[j];
                j++;
            }
            k++;
        }
​
        while (i < n1) {
            arr[k] = L[i];
            i++;
            k++;
        }
​
        while (j < n2) {
            arr[k] = R[j];
            j++;
            k++;
        }
    }

Question 8

Напиши пример алгоритма Quick Sort

Answer 8

public class QuickSort {
    public static void quickSort(int[] arr, int low, int high) {
        if (low < high) {
            int pi = partition(arr, low, high);
            quickSort(arr, low, pi - 1);
            quickSort(arr, pi + 1, high);
        }
    }

    public static int partition(int[] arr, int low, int high) {
        int pivot = arr[high];
        int i = (low - 1);
        for (int j = low; j < high; j++) {
            if (arr[j] < pivot) {
                i++;
                int temp = arr[i];
                arr[i] = arr[j];
                arr[j] = temp;
            }
        }
        int temp = arr[i + 1];
        arr[i + 1] = arr[high];
        arr[high] = temp;
        return i + 1;
    }

Question 9

Напиши пример алгоритма Heap Sort

Answer 9

public class HeapSort {
    public static void heapSort(int[] arr) {
        int n = arr.length;
        for (int i = n / 2 - 1; i >= 0; i--) {
            heapify(arr, n, i);
        }
        for (int i = n - 1; i > 0; i--) {
            int temp = arr[0];
            arr[0] = arr[i];
            arr[i] = temp;
            heapify(arr, i, 0);
        }
    }

    public static void heapify(int[] arr, int n, int i) {
        int largest = i;
        int left = 2 * i + 1;
        int right = 2 * i + 2;
        if (left < n && arr[left] > arr[largest]) {
            largest = left;
        }
        if (right < n && arr[right] > arr[largest]) {
            largest = right;
        }
        if (largest != i) {
            int swap = arr[i];
            arr[i] = arr[largest];
            arr[largest] = swap;
            heapify(arr, n, largest);
        }
    }

Question 10

Напиши пример алгоритма LinearSearch

Answer 10

public class LinearSearch {
    public static int linearSearch(int[] array, int target) {
        for (int i = 0; i < array.length; i++) {
            if (array[i] == target) {
                return i;
            }
        }
        return -1; // Целевой элемент не найден
    }

Question 11

Напиши пример алгоритма BinarySearch

Answer 11

public class BinarySearch {
    public static int binarySearch(int[] array, int target) {
        int left = 0;
        int right = array.length - 1;
        
        while (left <= right) {
            int mid = left + (right - left) / 2;
            
            if (array[mid] == target) {
                return mid;
            }
            if (array[mid] < target) {
                left = mid + 1;
            } else {
                right = mid - 1;
            }
        }
        return -1; // Целевой элемент не найден
    }