Java

class Node {
    char c;
    HashMap<Character, Node> children = new HashMap<Character, Node>();
    boolean isCompleteWord;

    public Node(char c) {
        this.c = c;
        isCompleteWord = false;
    }
    public Node() {
    }
}

List<String> collectWords(char c) {
    List<String> words = new ArrayList<>();
    String word = Character.toString(c);
    Node node = root.children.get(c);
    collectWordsHelper(words, node, word);
    return words;
}

void collectWordsHelper(List<String> words, Node node, String word) {
    for (char i = 'a'; i <= 'z'; i++) {
        if (node.children.containsKey(i)) {
            System.out.println(i); // prints the right letters
            Node child = node.children.get(i);
            word += i;
            if (child.isCompleteWord && !words.contains(word)) {
                words.add(word);
                collectWordsHelper(words, child, "");
            }
            collectWordsHelper(words, child, word);
        }
    }
}

Hello, How to solve this in Java? Generate random simple directed acyclic graph that user inserts the vertex number that each vertex has no less than K-min and not more than K-max neighbours of each vertex. In addition create function in program for given graph insertion and generated graph presentation by user(to print the graph). Generated graph is stored in adjacency list using one-dimensional array. In addtion, according to breadth-first search algortihtm find which vertex is farthest(longest path) from the given vertex and find the path distance. Print the found path between vertices.  If there are some vertices, it is enough one.