Blog, comments and tickets

How to read and write blog posts, comment under problems, report problem issues to their authors, follow your notifications and earn contribution points on LCOJ.

⏱ ~12 minutes · 👤 All members · 🔑 A signed-in LCOJ account (guests can only read)

Before you start

• You are signed in. Guests can read blog posts and comments, but cannot comment, vote or open tickets.
• You have solved at least 5 problems. This is required to comment and vote (staff are exempt).
• To write a blog post, you need at least 10 solved problems.
• You know basic Markdown. Math goes in ~...~ (inline) and $$...$$ (display).

Thresholds on LCOJ

Action	Requirement	Setting
Comment, vote on comments/posts	≥ 5 solved problems	VNOJ_INTERACT_MIN_PROBLEM_COUNT = 5
Write a personal blog post	≥ 10 solved problems	VNOJ_BLOG_MIN_PROBLEM_COUNT = 10
Comment	Contribution points ≥ −20	VNOJ_COMMENT_MIN_CONTRIBUTION = -20
Comment length	10 – 8196 characters	VNOJ_COMMENT_MIN_LENGTH, VNOJ_COMMENT_MAX_LENGTH
Tag problems from other judges	Rating ≥ 1900 or a dedicated permission	VNOJ_TAG_PROBLEM_MIN_RATING = 1900

"Solved problems" counts the public problems you have AC on. Staff are not bound by the solved-count, contribution and comment-length limits.

Blog

Reading posts

1. Open the home page at https://luyencode.net/. The blog box has two tabs:
   • Newsfeed (Tin tức): only posts staff marked as a global post (bài đăng chung); sticky (dán) posts stay on top.
   • Blogs (Blog): every public post, including members' personal blogs, newest first.
2. The home page remembers the tab you picked last. Further pages live at /posts/<page number>.
3. Click a title to open the post. Post URLs look like /post/<id>-<slug>.
4. To see all posts by one person, open their profile and choose the Blogs tab (/user/<name>/blog/).

The home page sidebar also shows ongoing and upcoming contests, the Comment stream (Dòng bình luận, the latest comments), new problems, the Top contributors table and My open tickets (Báo cáo của tôi), which lists the tickets you still have open.

Writing a post

1. Open your profile and pick the Create new blog post tab (Tạo blog mới), or go straight to /posts/new.
2. Fill in the post title (tiêu đề bài viết, up to 100 characters) and the post content (nội dung) in Markdown. Use the editor's preview tab to check it before publishing.
3. Tick public visibility (hiển thị công khai). This box is unticked by default: if you skip it, only you (and staff who can edit all posts) can see the post.
4. Click Create (Tạo). The post is published immediately and shows up in the Blogs tab on the home page.

Fewer than 10 solved problems

If you have not solved 10 problems yet, the page says You cannot create blog post. Note: You need to solve at least 10 problems to create new blog post. (Không thể tạo blog…).

After publishing:

• Edit: open the post and click [Edit] next to the title (/post/<id>-<slug>/edit). Authors can edit their own posts. Untick public visibility to hide the post.
• Delete: only users with the permission to delete posts (staff) see a Delete button. Regular members hide a post instead.
• Newsfeed / pinning: only staff with the mark_global_post / pin_post permissions see the global post and sticky boxes.

Markdown and math

Blog posts, comments and tickets all use Markdown, with support for tables, code blocks, strikethrough and spoilers.

To write	Syntax	Example
Inline math	~...~	~a^2 + b^2 = c^2~
Display math	$$...$$	$$\sum_{i=1}^{n} i = \frac{n(n+1)}{2}$$
Code block	Three backticks followed by the language name, e.g. cpp	Syntax-highlighted code

Don't use $...$

$a+b$ shows up as literal text. Always write inline math as ~a+b~.

In comments and tickets, raw HTML is escaped (shown as text). Blog posts allow a set of safe HTML tags.

Voting on posts

Each post has up/down arrows and its current score.

• You need ≥ 5 solved problems to vote; guests who click see Please log in to vote.
• You cannot vote on your own post (You cannot vote your own blog).
• You get one vote per post; voting again returns You cannot vote twice. instead of changing or removing your vote.
• Votes on public posts (not organization posts) are added to the authors' contribution points.

Organization blogs

Organization admins with the edit_organization_post permission can write posts for their organization at /organization/<slug>/post/new, without the 10-problem requirement. Organization posts are visible only to members of that organization and do not count toward contribution points. See Organizations.

Comments

Where comments appear

Page	Location
Problem	bottom of /problem/<code>
Editorial	bottom of /problem/<code>/editorial
Contest	on /contest/<key>
Blog post	bottom of /post/<id>-<slug>
Problem from another judge (tags)	on /tag/<code>

Comments load after the page opens, 20 top-level threads per page. If you see Comments are disabled on this page., comments there are locked: either staff locked them manually, or the problem/contest belongs to a running contest that uses clarifications.

Writing and replying

1. Scroll to the New comment box (Bình luận mới) at the end of the comments.
2. Write your comment in Markdown (10 – 8196 characters) and preview it if needed.
3. Click Post! (Đăng!).
4. To reply, click the Reply icon (Phản hồi) on a comment. You can only reply to comments posted within the last 365 days (DMOJ_COMMENT_REPLY_TIMEFRAME).

The Link icon (Liên kết) gives you a direct link to the comment (#comment-<id>).

Where to ask for help?

Ask for hints in the comments, not in a ticket. Tickets are only for problems with a statement, its tests or the site itself.

Votes and hidden comments

• Each comment has up/down arrows. The rules match blog voting: ≥ 5 solved problems, no voting on your own comments (You cannot vote on your own comments.), one vote per person.
• Each vote changes the author's contribution points by 1 (VNOJ_CP_COMMENT = 1).
• Comments with a score of −5 or lower (DMOJ_COMMENT_VOTE_HIDE_THRESHOLD) are collapsed behind This comment is hidden due to too much negative feedback. Click Show it anyway. (Nhấn để xem.) to read it.

Editing, deleting and reporting comments

• Edit: click the Edit icon on your own comment. Edited comments show edited (chỉnh sửa) with ← → arrows to step through earlier revisions.
• Delete: members cannot delete their comments. To take one down, edit it or ask staff.
• Staff also get a Hide button (Ẩn): it hides the comment and all replies under it, and the author's contribution points are recalculated (hidden comments no longer count).
• Reporting an abusive comment: there is no per-comment report button. Use the Report issue button in the navigation bar (see Tickets below) and paste the comment's link into the description.

Comment mute

Accounts that staff put on comment mute (tắt bình luận) cannot comment, vote, edit comments or open tickets, and see Your part is silent, little toad. plus the reason, if one was given.

Contribution points

Contribution points recognize how you help the community. They are calculated as follows:

Source	Points
Each up / down vote on your comments (non-hidden comments)	+1 / −1
Each up / down vote on your public posts (not organization posts)	+1 / −1
Each ticket marked good	+5 (VNOJ_CP_TICKET = 5)
Each time you unlock the editorial of a problem you haven't solved	−1

Where to see them:

• On your profile, the Contribution points: line (Đóng góp:).
• The contribution ranking at /contributors/ (the Contributors tab next to Leaderboard). The Search by handle... box jumps to the page containing that user.
• The Top contributors table on the home page (top 5).

Negative points

With contribution points below 0, you cannot unlock editorials for problems you haven't solved. Below −20, you can no longer comment.

Tickets (reporting issues)

A ticket is a private channel between you and the people responsible, for reporting a wrong statement, broken tests or a site issue. Only you, the assignees and staff can see a ticket.

Reporting a problem issue

1. Open the problem and click Report an issue (Báo cáo vấn đề) below the statement, or the Report issue button in the navigation bar. In a contest where comments are locked, the button below the statement reads Request clarification (Gửi thắc mắc) instead.
2. The page /problem/<code>/tickets/new opens. Fill in the Ticket title (up to 100 characters) and the Issue description in Markdown: which test, the expected result, and why you think the statement or test is wrong.
3. Click Create! (Tạo!). You are taken to the ticket page, /ticket/<number>.

The ticket is automatically assigned to the problem's authors and curators. If you are in a contest and the problem belongs to that contest, it goes to the contest's authors and curators instead.

Tickets are not for asking for help

The form says it plainly: tickets are for reporting issues with a problem, not for asking how to solve it. Ask for hints in the comments. Misusing tickets can get your account banned.

Reporting a general issue

On any page other than a problem statement, the Report issue button in the navigation bar opens /tickets/new?issue_url=<current page>. The Link to the issue field (URL tới vấn đề) is prefilled with the page you were on and is required. Add a title and description, then click Create!.

General tickets are not assigned to anyone in particular; staff follow them in the ticket list.

Following up on a ticket

• See your tickets at /tickets/. Tick Show my tickets only or Hide closed tickets and click Go (Tìm) to filter. On a problem page, the My tickets link (/problem/<code>/tickets/) lists your tickets for that problem.
• On the ticket page, type your reply in the box at the bottom and click Post!. The page updates live when new messages arrive.
• As the reporter, you can Close ticket (Đóng vấn đề) once it is resolved, or Reopen ticket (Mở lại vấn đề) if the issue comes back.

What staff and assignees see

Who	Can see and do
Reporter	Their own tickets: reply, close/reopen
Assignees (authors, curators)	Tickets assigned to them; private Assignee notes; Upvote (mark good) and Undo vote (unmark) buttons
Users who can edit the problem	All tickets for the problem via Manage tickets on the problem page
Staff with change_ticket	Every ticket, including general ones

Reporters cannot mark their own ticket as good (You cannot vote your own ticket.). Staff also see a New tickets box on the home page.

Notifications

The bell icon in the navigation bar shows your unread notification count.

1. Click the bell to open the unread panel (up to the 10 most recent).
2. Click a notification to follow its link; it is marked as read.
3. Click Mark all read to mark everything as read.
4. Click See all notifications for the full page at /notifications/, with All / Unread / Read filters and a Mark all as read button.

What creates a notification:

Event	Who receives it
New ticket on a problem/contest	Assignees
Someone else replies to your ticket	The reporter
The reporter replies to a ticket	Assignees
A contest posts an announcement	All official participants of the contest (not virtual ones)

Contest announcements are sorted first, then ticket notifications. Closing or reopening a ticket does not create an inbox notification, although an open ticket page updates live.

English labels

Some notification labels (Mark all read, See all notifications, Unread…) are not translated yet, so they appear in English in the Vietnamese interface too.

Tagging problems from other judges

The /tags/ page is a collection of problems from other online judges (AtCoder, Codeforces, Codeforces Gym, Kattis, VNOJ) that the community tags with algorithm topics. These are not LCOJ problems, so you cannot submit to them here. In the list, click a problem's code or name to see its tag page; click the judge name to open the original statement.

Finding problems

1. Open /tags/ (Tag problem list, Danh sách bài).
2. Click a tag in the tag groups to filter by it; type a code or name into Search problems...; pick judges in the online judge filter.
3. Click Go to filter, or Random (Ngẫu nhiên) to open a random matching problem (in a new tab). Clear search resets all filters.
4. Each problem's page (/tag/<code>) lists its tags, who assigned them, and a comment section; the page title links to the original statement. Tags may be inaccurate; leave a comment or use Report issue if one looks wrong.

Who can add problems and tags

You can tag problems when both of these hold:

• Your profile has Allow tagging (Cho phép tag bài) enabled. It is on by default; staff can turn it off per user.
• You have the add_tagproblem permission, or a rating of 1900 or more.

Otherwise the page says Cannot tag – You are not allowed to tag problem.

How to do it:

1. On /tags/, pick the Create new tag problem tab (Thêm tag cho bài, /tags/create), paste the problem URL from the original judge, e.g. https://codeforces.com/problemset/problem/4/A, and click Create. Fetching data from the original judge can take a few minutes.
2. If the problem already exists, you are redirected to its page.
3. On the problem's page, click Assign new tag (Thêm tag mới), choose tags and click Assign (Thêm).

FAQ

Question / Symptom	Answer
No comment box, only "You need to have solved at least 5 problems before your voice can be heard."	Solve enough public problems (AC) to reach 5, then reload.
Voting says "You must solve at least 5 problems before you can vote."	Same as above: you need 5 solved problems.
My post is published but others can't see it	You didn't tick public visibility. Open [Edit], tick it and click Update.
My post isn't in the Newsfeed tab	That tab only shows posts staff marked as global post. Personal posts appear under Blogs.
There's no Reply icon on a comment	The comment is older than 365 days, or comments on that page are locked.
I voted by mistake and want to change it	Votes cannot be changed or removed from the interface.
How do I report an abusive comment?	Use Report issue in the navigation bar and paste the comment's link (from the Link icon) into the description.

Next steps

• Account and profile: edit your profile and view your stats.
• Organizations: join an organization and write internal posts.
• FAQ: quick answers to other common questions.