style: format markdown files with remark-lint

  bool operator<(const student& a) const {

    return score < a.score || (score == a.score && name > a.name);

    // 上面省略了 this 指针，完整表达式如下：

    // this -> score < a.score || (this -> score == a.score && this -> name > a.name);

    // this -> score < a.score || (this -> score == a.score && this -> name >

    // a.name);

  }

};

priority_queue<student> pq;