Sorting.java

import java.util.Arrays;
import java.util.Collections;

public class Sorting {
    public static void BubbleSort(int arr[]) {
        for(int turn =0; turn<arr.length - 1; turn++) {
            for(int j =0; j<arr.length-1-turn; j++) {
                if (arr[j] > arr[j+1]) {
                    //swap
                    int temp = arr[j];
                    arr[j] = arr[j+1];
                    arr[j+1] = temp;
                }
            }
        }
    }
    public static void SelectionSort(int arr[]) {
        for(int i=0;i<arr.length-1;i++) {
            int Minpos = i;
            for(int j=i+1;j<arr.length;j++) {
                if (arr[Minpos] > arr[j]) {
                    Minpos =j;
                }
            }
            //swap
            int temp = arr[Minpos];
            arr[Minpos] = arr[i];
            arr[i] = temp;
        }
    }
    public static void InsertionSort(int arr[]) {
        for(int i=1;i<arr.length;i++) {
            int curr = arr[i];
            int prev = i-1;
            //Finding out the current position to insert.
            while (prev >=0 && arr[prev] > curr) {
                arr[prev + 1] = arr[prev];
                prev--;
            }
            //insertion.
            arr[prev + 1] = curr;
        }
    }
    public static void countingsort(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]]++;
        }
        //sorting
        int j=0;
        for(int i =0;i<count.length;i++) {
            while (count[i] >0) {
                arr[j] =i;
                j++;
                count[i]--;
            }
        }
    }
    public static void PrintArray(int arr[]) {
        for(int i=0;i<arr.length;i++) {
            System.out.print(arr[i] + " ");
        }
        System.out.println();
    }
    public static void main(String[] args) {
        //int arr[] = {5,4,1,3,2};
        //Integer arr[] = {5,4,1,3,2};
        //Arrays.sort(arr);
        //Arrays.sort(arr,0,3);
        //Arrays.sort(arr,Collections.reverseOrder());
        //Arrays.sort(arr,0,3,Collections.reverseOrder());                                          // -- InBuilt sort. 
        //BubbleSort(arr);
        //SelectionSort(arr);
        //InsertionSort(arr);
        int arr[] = {1,4,1,3,2,4,3,7};
        countingsort(arr);
        PrintArray(arr);
    }
}