text: const { NotImplementedError } = require('../extensions/index.js');
  
  /**
   * Given an array of domains, return the object with the appearances of the DNS.
   *
   * @param {Array} domains
   * @return {Object}
   *
   * @example
   * domains = [
   *  'code.yandex.ru',
   *  'music.yandex.ru',
   *  'yandex.ru'
   * ]
   *
   * The result should be the following:
   * {
   *   '.ru': 3,
   *   '.ru.yandex': 3,
   *   '.ru.yandex.code': 1,
   *   '.ru.yandex.music': 1,
   * }
   *
   */
  function getDNSStats(domains) {
  
    const obj = {};
    for (const domain of domains) {
      const currDomain = domain.split('.');
      let acc = '',
          index = currDomain.length - 1;
      while (index >= 0) {
        acc += '.' + currDomain[index];
        if (!obj[acc]) obj[acc] = 0;
        obj[acc]++;
        index--;
      }
    }
    return obj;
  }
  
  module.exports = {
    getDNSStats
  };
  