Main.java

import java.util.*;

class Main {
    public static void main(String[] args) {
        System.out.println(modifyStr("").equals(""));
        System.out.println(modifyStr("Automotive parts").equals("A6e p3s"));
        System.out.println(modifyStr("Automotive par").equals("A6e p1r"));
        System.out.println(modifyStr("Automotive pa").equals("A6e p0a"));
        System.out.println(modifyStr("Automotive p").equals("A6e p0p"));
        System.out.println(modifyStr("**Automotive p").equals("**A6e p0p"));
        System.out.println(modifyStr("*Automotive* p").equals("*A6e* p0p"));
    }

    static String modifyStr(String input) {
        // empty check
        if (input == null || input.equals("")) return input;

        String output = "";
        int wordStart = 0;
        int delimit = 0;

        while (wordStart < input.length()) {
            // find the start index of word
            while (!Character.isAlphabetic(input.charAt(wordStart))) {
                output += input.charAt(wordStart);
                wordStart++;
            }

            // find the delimit index of word
            delimit = wordStart + 1;
            while (delimit < input.length() &&
                    Character.isAlphabetic(input.charAt(delimit))) {
                delimit++;
            }

            // find the count of distinct letters
            HashSet<Character> set = new HashSet<>();
            for (int i = wordStart+1; i < delimit-1; i++) {
                set.add(input.charAt(i));
            }

            output += String.valueOf(input.charAt(wordStart)) + set.size() +
                    String.valueOf(input.charAt(delimit-1));

            wordStart = delimit;
        }
        return output;
    }
}

PP 1.6: In the language of your choice, write a method that modifies a string using the following rules:

1. Each word in the input string is replaced with the following: the first letter of the word, the count of
   distinct letters between the first and last letter, and the last letter of the word. For example,
   “Automotive parts" would be replaced by "A6e p3s".
2. A "word" is defined as a sequence of alphabetic characters, delimited by any non-alphabetic
   characters.
3. Any non-alphabetic character in the input string should appear in the output string in its original
   relative location.