/**
     * Find the first string within a list which creates a prefix
     * relationship with any other string. 
     *
     * Applies a sorted map. Reporting the first occurrence is
     * rather troublesome: This requires tracking the index of
     * each prefix relationship and making a second pass.
     *
     * 𝚯(N log N)
     * 𝚯(N) space (red-black tree)
     *
     * https://github.com/profinite/HackerRank/
     */
    public static void noPrefix(List<String> words) {
       TreeMap<String, Integer> sorted = new TreeMap<>();
       int min = Integer.MAX_VALUE; // index of first observable prefix
       int index = 0;
       for (String word : words) {
            if (sorted.containsKey(word)) // check for identical
                min = Math.min(min, index);
            sorted.putIfAbsent(word, index++); // sort the strings
        }
        for (String word : words.stream().distinct().toList()) {
            String next = sorted.higherKey(word);
            while (isPrefix(word, next)) {
                min = Math.min(min, Math.max(sorted.get(word), sorted.get(next)));
                next = sorted.higherKey(next);
            }
        }
        if(min != Integer.MAX_VALUE)
            System.out.println("BAD SET\n" + words.get(min));
        else
            System.out.println("GOOD SET");
    }
    static boolean isPrefix(String pre, String full) {
        return pre != null && full != null && full.startsWith(pre);
    }