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| Filename | Latest commit message | Latest commit date |
|---|---|---|
Azer
4bc73e3175
Codeforces refuses a handle no user can have with a 400 and a reason such as "handle: Field should contain between 3 and 24 characters, inclusive". That was taken for a passing failure: the line under the field quoted the raw reason in English on either page, and the next draw loaded the handle again. Typing "ab" cost a second call and a 1.9 s wait on the first draw. It is treated like a user that does not exist: "Codeforces does not accept "ab" as a handle." in either language, one call, and draws that do not wait for it. |
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| .forgejo/workflows | ||
| .github/workflows | ||
| modules | ||
| styles | ||
| test | ||
| index.html | ||
| package.json | ||
| README.md | ||
| script.js | ||
Random Codeforces problem Generator
A random Codeforces problem in the rating range and topics you choose, skipping the ones you have already solved.
Live: https://azer.is-a.dev/random-cf-problem/
What it does
- Draws a rated problem between a minimum and a maximum rating.
- Narrows by topics: all of the chosen ones, any of them, or none of them. A line above the button says how many problems the settings leave.
- Optionally leaves out the problems Codeforces tags
*special: April Fools contests, Kotlin Heroes, Q# and unknown-language rounds, olympiad mirrors. - Skips problems solved by one or more handles (up to five, separated by commas or spaces), and optionally the ones they tried too. A problem solved in the parallel Div. 1 or Div. 2 round counts as solved.
- Shows the problem's rating in its Codeforces rank colour and how many people solved it; the topics can be hidden, and shown again for the problem on screen when you get stuck.
- Lists the last ten draws and avoids repeating them while anything else matches.
- Remembers the settings, and keeps them in the address so a link reproduces them.
Rdraws again; Enter in any field does too.- English and Russian; follows the system's light or dark theme; fits a phone.
Link parameters
| Parameter | Example | Meaning |
|---|---|---|
min, max |
min=1400&max=1900 |
rating range, inclusive |
tags |
tags=dp,graphs |
topics, as Codeforces names them |
any |
any=1 |
any of the topics rather than all of them |
none |
none=1 |
none of the topics |
nospecial |
nospecial=1 |
leave out special rounds |
skip |
skip=tourist,jiangly |
skip what these handles solved |
tried |
tried=1 |
also skip what they tried |
hide |
hide=1 |
hide the drawn problem's topics |
lang |
lang=ru |
en or ru; remembered |
How it works
Everything runs in the browser against the public Codeforces API. The
whole problemset (problemset.problems) is fetched once and kept in the
browser's Cache Storage for a day; an older copy is used straight away
while a fresh one loads, and "Refresh" at the bottom fetches it on demand.
For each handle to skip, user.status is boiled down to the problems it
solved and tried, and kept for ten minutes; the start times from
contest.list, which tell parallel rounds apart, are kept for a day.
Calls to the API are spaced two seconds apart, as Codeforces asks.
Running it locally
Any static file server will do; the page loads ES modules, which browsers
refuse to do from file://:
npx http-server -p 4341
The logic that does not touch the page lives in modules/ and is tested
with Node's built-in runner, no dependencies needed:
npm test
Important point
The code has NOT been polished and is provided "as is". There's a lot of code that is redundant and there are tons of improvements that can be made.