Method insert

java/720_Longest_Word_in_Dictionary.java:48–55

(String word, int index)

    }

    public void insert(String word, int index) {
        Node cur = root;
        for (char c: word.toCharArray()) {
            cur.children.putIfAbsent(c, new Node(c));
            cur = cur.children.get(c);
        }
        cur.end = index;
    }

    public String dfs() {
        String ans = "";