CountSort.java

public class CountSort {

    public static void countingsort(int arr[]) {
         int max = Integer.MIN_VALUE;
          // Finding the Maximum value of orignal Array
         for(int i=0;i<arr.length;i++){
            max = Math.max(arr[i], max);
         }
         //Creating a Frequency array of Length of Maximum value +1 of Orignal Array
         int count [] = new int[max+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]--;
            }
         }
          // Returning the Sorted Array
         for(int i=0;i<arr.length ;i++){
            System.out.print(arr[i]+", ");
         }
    }
    public static void main(String[] args) {

        int arr[] = {1,4,1,4,2,3,7}; // Test Array
        countingsort(arr); // Calling Function
    }
}