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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]+" ");

}

}

}