import java.util.ArrayList;
import java.util.Map;
import java.util.TreeMap;

/**
 *
 * @author Youssef Ali (https://github.com/youssefAli11997)
 *
 */

class CountingSort {

    /**
     * This method implements the Generic Counting Sort
     *
     * @param array The array to be sorted 
     * @param last The count of total number of elements in array
     * Sorts the array in increasing order
     * It uses array elements as keys in the frequency map
     **/
	    
    public static <T extends Comparable<T>> void CS(T[] array, int last) {
    
    	Map<T, Integer> frequency = new TreeMap<T, Integer>();
    	// The final output array
    	ArrayList<T> sortedArray = new ArrayList<T>();
    	
    	// Counting the frequency of @param array elements
    	for(T t : array) {
    		try{
    			frequency.put(t, frequency.get(t)+1);
    		}catch(Exception e){ // new entry
    			frequency.put(t, 1);
    		}
        }
    	
    	// Filling the sortedArray
    	for(Map.Entry<T, Integer> element : frequency.entrySet()) {
            for(int j=0; j<element.getValue(); j++)
                sortedArray.add(element.getKey());
        }
    	
    	for(int i=0; i<array.length; i++){
    		array[i] = sortedArray.get(i);
    	}
    }

    // Driver Program
    public static void main(String[] args) {
        // Integer Input
        Integer[] arr1 = {4,23,6,78,1,54,231,9,12};
        int last = arr1.length;
        
        System.out.println("Before Sorting:");
        for (int i=0;i<arr1.length;i++) {
            System.out.print(arr1[i] + " ");
        }
        System.out.println();

        CS(arr1, last);

        // Output => 1 4 6 9 12 23 54 78 231
        System.out.println("After Sorting:");
        for (int i=0;i<arr1.length;i++) {
            System.out.print(arr1[i] + " ");
        }
        System.out.println();
        
        System.out.println("------------------------------");
        
        // String Input
        String[] array1 = {"c", "a", "e", "b","d"};
        last = array1.length;
        
        System.out.println("Before Sorting:");
        for (int i=0;i<array1.length;i++) {
            System.out.print(array1[i] + " ");
        }
        System.out.println();

        CS(array1, last);

        //Output => a	  b	 c	d	e
        System.out.println("After Sorting:");
        for(int i=0; i<last; i++) {
            System.out.print(array1[i]+" ");
		}
		
    }
}