BasicSorting.java

public class BasicSorting {

    public static void Bubble(int arr[]) {
        for (int i = 0; i < arr.length - 1; i++) {
            for (int j = 0; j < arr.length - 1 - i; j++) {  // sorting in descending order
                if (arr[j] < arr[j + 1]) {
                    int temp = arr[j];
                    arr[j] = arr[j + 1];
                    arr[j + 1] = temp;
                }
            }
        }
    }

    public static void Selection(int arr[]) {
        for (int i = 0; i < arr.length; i++) {
            int maxPos = i;
            for (int j = i + 1; j < arr.length; j++) {
                if (arr[maxPos] < arr[j]) {
                    maxPos = j;
                }
            }
            int temp = arr[maxPos];
            arr[maxPos] = arr[i];
            arr[i] = temp;
        }
    }

    public static void Insertion(int arr[]) {
        for (int i = 1; i < arr.length; i++) {
            int curr = arr[i];
            int prev = i - 1;
            while (prev >= 0 && arr[prev] < curr) {
                arr[prev + 1] = arr[prev];
                prev--;
            }
            arr[prev + 1] = curr;
        }
    }

    public static void countingSortDescending(int arr[]) {
        int largest = Integer.MIN_VALUE;
        for (int i = 0; i < arr.length; i++) {
            largest = Math.max(largest, arr[i]);
        }
        int count[] = new int[largest + 1];
        for (int i = 0; i < arr.length; i++) {
            count[arr[i]]++;
        }
        int j = 0;
        for (int i = count.length - 1; i >= 0; i--) {
            while (count[i] > 0) {
                arr[j] = i;
                j++;
                count[i]--;
            }
        }
    }

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

    public static void main(String[] args) {
        int arr[] = {3, 2, 5, 4, 1};
        // Bubble(arr);
        // Selection(arr);
        // Insertion(arr);
        countingSortDescending(arr);
        print(arr);
    }
}