Authoring a Problem of the Day

Each problem is one JSON file in this directory containing everything: the statement, the samples, the hidden tests, and the checker. Because the hidden tests live here, this repo is private to the setting team.

Flow

1. Copy an existing file as a starting point.
2. Name it YYYY-MM-DD-kebab-title.json, where the date is the day it should go live. Future-dated files are not served by the app — the statement, its samples, and its hidden tests stay invisible until that date arrives — so you can queue problems ahead of time.
3. Open a PR. The Validate challenges GitHub Action runs the schema check (npm run challenges:validate) and must pass before merge.
4. An admin merges. It releases automatically at the top of its date.

Schema

Field	Required	Notes
schemaVersion	–	Integer. Currently 1.
slug	–	Lowercase letters/digits/hyphens. Defaults to the filename; if set, must match it.
title	✓	Display title.
difficulty	–	One of Easy, Medium, Hard, Unrated.
tags	–	Array of strings.
date	✓	YYYY-MM-DD, a real calendar date. Release day.
timeLimit	–	e.g. "1s", "500ms". Enforced by the judge (TLE).
memoryLimit	–	Display only for now, e.g. "256 MB".
author	–	Credit line.
statement	✓	Markdown. Inline code and fenced blocks render.
inputFormat / outputFormat / constraints	–	Markdown.
samples	✓	≥1 { input, output, explanation? }. Shown to solvers.
tests	✓	≥1 { input, output }. Hidden — never sent to the client.
checker	–	{ "type": "token" | "exact" | "float", "epsilon"? }. Defaults to token.

There is no points field — scoring comes from the speed-bounty ladder (finish order), not the problem file.

Checkers

• token (default): whitespace-insensitive token-by-token match. Use for most integer/string answers.
• exact: byte-for-byte (trailing newlines ignored). Use when spacing matters.
• float: token match with numeric tolerance epsilon (default 1e-6).

Validate locally

npm run challenges:validate