private void printArray(char result[], boolean used[]){
        for(int i=0; i < used.length; i++){
            if(used[i]){
                System.out.print(result[i] + " ");
            }else{
                System.out.print("* ");
            }
        }
        System.out.println();
    }
e.g a, b c 
* * *
a * *
a b *
a b c
* b *
* b c
* * c

Idea is to store the index of values in used[] array. So just
like regular combination if used is set print it else print *
src/com/interview/recursion/CombinationWithStar.java