老师您好，
在完成lc642这道题中，我想用trie来完成，想请问一下老师以下代码的思路是否正确，以及如何实现input这个函数？
谢谢老师！
class AutocompleteSystem {

private class Node {
    public int times;
    public Map<Character, Node> next;
    
    public Node(int times) {
        this.times = times;
        next = new HashMap<>()
    }
    
    public Node() {
        this(0);
    }
}

private Node root;

private void insert(String sentence, int times) {
    Node cur = root;
    for (int i = 0; i < sentence.length(); i++) {
        char c = sentence.charAt(i);
        if (cur.next.get(c) == null) {
            cur.next.put(c, new Node());
        }
        cur = cur.next.get(c);
    }
    cur.times = times;
}

public AutocompleteSystem(String[] sentences, int[] times) {
    root = new Node();
    for (int i = 0; i < sentences.length; i++) {
        insert(sentences[i], times[i]);
    }
    
}

public List<String> input(char c) {
    List<String> result = new ArrayList<>();
    
}

}