CountAndRadix.java

import java.util.*;


class Pair {

    public byte count;

    public List<String> words;

    public Pair() {
        words = new LinkedList<>();
        count = 0;
    }
}

public class CountAndRadix {

    static int max = 0;

    static int findLongestString(String... arr) {

        int maxLength = 0;
        for (String s : arr) {
            if (s.length() > maxLength) {
                maxLength = s.length();
            }
        }
        return maxLength;

    }

    static String[] util(String... arr) {

        max = findLongestString(arr);

        String res[] = new String[arr.length];
        int i = 0;
        for (String string : arr) {

            while (string.length() < max) {
                string = string.concat("}");

            }

            res[i++] = string;
        }
        return res;
    }

    public static void main(String[] args) {

        String input[] = {"ab", "ab", "aa", "zd", "ac"};

        String[] arr = util(input);

        List<Pair> count = new ArrayList<>(126);

        for (int i = 0; i < 126; i++) {

            count.add(new Pair());

        }

        for (int j = 1; j <= arr[0].length(); j++) {

            for (String arr1 : arr) {
                Pair pair = count.get(arr1.charAt(arr[0].length() - j));
                pair.count++;
                pair.words.add(arr1);
            }


            int i = 0;

            for (int k = 96; k < count.size(); k++) {
                Pair pair = count.get(k);
                if (pair.count != 0) {
                    for (String word : pair.words) {
                        arr[i++] = word;
                    }
                }
            }


            count.forEach((pair) -> {
                pair.words.clear();
            });

        }

        for (int i = 0; i < arr.length; i++) {
            StringBuilder r = new StringBuilder(arr[i]);

            for (int j = 0; j < r.length(); j++) {

                if (r.charAt(j) == '}') {
                    r = r.deleteCharAt(j);
                    j--;
                }
            }

            System.out.print(r + " ");
        }

    }

}