Comments

function solve(arr) {
  let users = [];
  let articles = new Map();

  for (let info of arr) {
    if (info.includes('article')) {
      const article = info.substring(info.indexOf(' ') + 1,);
      articles.set(article, new Map());
    } else if (info.includes('user')) {
      const user = info.substring(info.indexOf(' ') + 1,);
      users.push(user);
    } else {
      const user = info.substring(0, info.indexOf(' '));
      const article = info.substring(info.indexOf('on') + 3, info.indexOf(':'));
      const title = info.substring(info.indexOf(':') + 2, info.indexOf(','));
      const comment = info.substring(info.indexOf(',') + 2,);
      if (doesExistUser(user) && doesExistArticle(article)) {
        const cmToPush = [title, comment];
        if (!doesUserExistInArticle(user, article)) {
          articles.get(article).set(user, []);
        }
        findUserComments(user).push(cmToPush);
      }
    }
  }

  // console.log(articles);

  for (const article of [...articles.entries()].sort((a, b) => compare(a, b))) {
    console.log(`${article[0]}`);
  }



  function doesExistUser(x) {
    return users.includes(x);
  }

  function doesExistArticle(x) {
    return articles.has(x);
  }

  function doesUserExistInArticle(x, y) {
    return articles.get(y).has(x);
  }

  function findUserComments (x) {
    for (let article of articles.entries()) {
      if (article[1].has(x)) {
        return article[1].get(x);
      }
    }
  }

  function compare(a,b) {
    // let art1 = [...a.entries()];
    // let art2 = [...b.entries()];
    // return [...art1[1].values()].reduce((a,b) => a + b.length,0) - [...art2[1].values()].reduce((a,b) => a +b.length,0);
    return [...a[1].values()].reduce((a,b) => a + b.length, 0) - [...b[1].values()].reduce((a,b) => a + b.length, 0);
  }
}