public class CountingSort
{
    public static void sort(char arr[])
    {
        int n = arr.length;
 
        // The output character array that will have sorted arr
        char output[] = new char[n];
 
        // Create a count array to store count of inidividul
        // characters and initialize count array as 0
        int count[] = new int[256];
        for (int i = 0; i < 256; ++i)
            count[i] = 0;
 
        // store count of each character
        for (int i=0; i<n; ++i)
            ++count[arr[i]];
 
        // Change count[i] so that count[i] now contains actual
        // position of this character in output array
        for (int i = 1; i <= 255; ++i)
            count[i] += count[i-1];
 
        // Build the output character array
        for (int i = 0; i < n; ++i)
        {
            output[count[arr[i]] - 1] = arr[i];
            --count[arr[i]];
        }
 
        // Copy the output array to arr, so that arr now
        // contains sorted characters
        for (int i = 0; i<n; ++i)
            arr[i] = output[i];
    }
 
    public static void main(String args[])
    {
        char arr[] = {'h','a','c','k','t','o','b','e','r','f','e','s','t'};
        
        sort(arr);
        System.out.print("Sorted character array is ");
        for (int i=0; i<arr.length; ++i)
            System.out.print(arr[i]);
    }
}