"use strict";

const util = require('util')

class TrieNode {
    constructor(l) {
        this.letter = l;
        this.isFullWord = false;
        this.letters = {};
        this.wordCount = 0;
    }

    isAdjacent(letter) {
        return letter in this.letters
    }

    add (name, i) {

        this.wordCount++;

        if ( name.length == i ) {
            this.isFullWord = true;
            return
        }

        let letter =  name[i];
        if (!this.isAdjacent(letter)) {
            this.letters[ letter ] = new TrieNode(letter);
        }

        this.letters[ letter ].add( name, i+1 );
    }

    countByPrefix (prefix, i) {
        let wordCount = 0;
        if (prefix.length == i) {
            wordCount = this.wordCount;
        } else {
            let letter = prefix[i];
            if (letter in this.letters) {
                wordCount = this.letters[ letter ].countByPrefix(prefix, i+1)
            }
        }
        return wordCount;
    }
}

class Agenda {

    constructor() {
        this.agenda = {};
    }

    addContact(name) {
        let letter = name[0];

        if (! (letter in this.agenda)) {
            this.agenda[ letter ] = new TrieNode(letter);
        }

        this.agenda[ letter ].add(name, 1);
    }

    countByPrefix(prefix) {
        let letter = prefix[0];

        if ( letter in this.agenda ) {
            return this.agenda[ letter ].countByPrefix(prefix, 1);
        }

        return 0
    }
}


let agenda = new Agenda();

agenda.addContact("s");
agenda.addContact("ss");
agenda.addContact("sss");
agenda.addContact("ssss");
agenda.addContact("sssss");
console.log(agenda.countByPrefix("s"))
console.log(agenda.countByPrefix("ss"))
console.log(agenda.countByPrefix("sss"))
console.log(agenda.countByPrefix("ssss"))
console.log(agenda.countByPrefix("sssss"))
console.log(agenda.countByPrefix("ssssss"))


console.log("=====")

agenda.addContact("hack");
agenda.addContact("hackerrank");


console.log(agenda.countByPrefix("hac"))
console.log(agenda.countByPrefix("hak"))
console.log(agenda.countByPrefix("hackerrank"))