GCPC-2k26-Challenges

Contest challenges for GDG Algiers — GCPC 2026.

Problems

Label	Name	Author	Difficulty	Status
A	Dungeon Escape	Lyes Boudjabout	Easy	Published
B	Festival Queue Merges	Lyes Boudjabout	Easy	Published
C	Relief Distribution	Lyes Boudjabout	Easy	Published
D	Latency Budget	Bouzara Zakaria	Easy	Published
E	Arduino Breadboard Setup	Raouf Ould Ali	Medium	Published
F	Circuit Breaker	Bouzara Zakaria	Medium	Published
G	Cloud Battle	Redhouane Abdellah	Medium	Published
H	Emergency Lane	tarek-ait	Medium	Published
I	Permutation Riddle	Redhouane Abdellah	Medium	Published
J	The Sarrus Oracle	tarek-ait	Medium	Published
K	Rassim Sort	Redhouane Abdellah	Medium	Published
L	Midnight Relay Tour	tarek-ait	Medium	Published
M	DzNet Signal Coverage	Nabil Ghemam Djeridi	Medium	Published
N	AI Simulation on Uncle Island	Firas Mohamed Elamine KiNram	Hard	Published
O	Hoggar Trail	Firas Mohamed Elamine Kiram	Hard	Published
P	Card Tricks	Raouf Ould Ali	Hard	Published
Q	Quantum Pyramid	Raouf Ould Ali	Hard	Published

Status lifecycle: draft → ready → tested → published Update this table and contest.yaml together when adding/changing a problem.

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Adding a New Challenge

1. Copy challenge_template/ → challenges/<problem-id>/
   • Use a short lowercase slug as the folder name, e.g. robery or allo-nokia
   • This folder name becomes the problem's external ID in DOMjudge
2. Generate a UUID and put it in problem.yaml:

   python3 -c "import uuid; print(uuid.uuid4())"

3. Fill in problem.yaml (name, time_limit) and domjudge-problem.ini (color)
4. Write the statement in statement/problem.md
5. Add test cases to data/sample/ and data/secret/ as .in/.ans pairs
6. Replace the skeleton solutions in submissions/accepted/ with real solutions in all 6 languages (c, cpp, py, go, js, java)
7. Write the editorial in editorial/editorial.md
8. Add an entry to contest.yaml and update the table above

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Test Case Format

Sample vs Secret

Folder	Visible to contestants?	Purpose
data/sample/	Yes — shown in problem statement	The same examples printed in the PDF. Contestants can run these themselves.
data/secret/	No — hidden during contest	The real judging test cases. Cover edge cases, large inputs, stress tests, etc.

DOMjudge imports test cases by scanning for *.in / *.ans pairs.
Do not use .txt — DOMjudge ignores files that don't match these extensions.

File naming

data/
├── sample/
│   ├── 1.in        ← sample test case 1 input
│   └── 1.ans       ← sample test case 1 expected output
└── secret/
    ├── 01.in       ← zero-padded so they sort correctly
    ├── 01.ans
    ├── 01.desc     ← one-liner describing what this case tests (for authors only)
    ├── 02.in
    ├── 02.ans
    └── 02.desc

.desc files

Optional one-line description of what a secret test case tests. DOMjudge stores this and shows it to the jury. Examples:

edge case: n=1
maximum input: n=100000, all elements equal
random large input
adversarial case: strictly decreasing sequence

Important rules

• No Windows line endings (\r\n) — use Unix line endings (\n) only
• Both .in and .ans must end with a newline
• Sample test cases must exactly match the examples printed in statement/problem.md

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DOMjudge Verdict Types

When a submission is judged, DOMjudge returns one of these verdicts:

Verdict	Meaning
AC — Accepted	Output matches .ans for all test cases within time and memory limits
WA — Wrong Answer	Output doesn't match .ans on at least one test case
TLE — Time Limit Exceeded	Solution ran longer than timelimit seconds on at least one case
MLE — Memory Limit Exceeded	Solution used more memory than the memory limit
RTE — Run-Time Error	Solution crashed (segfault, exception, non-zero exit code)
CE — Compile Error	Solution failed to compile
NO — No Output	Solution produced empty output

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Supported Languages

All accepted solutions must be provided in all 6 languages:

Language	Extension	Notes
C	.c	gcc, C17
C++	.cpp	g++, C++17
Java	.java	OpenJDK — class name must match filename
Python 3	.py	CPython 3
Go	.go	Go 1.20 (custom-installed on judgehosts)
JavaScript	.js	Node.js

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Testing a Solution Locally

Run from inside the problem directory:

cd challenges/<problem-id>

# pre-compiled binary
../../scripts/solution_test.sh ./sol

# auto-compiled/interpreted source
../../scripts/solution_test.sh submissions/accepted/sol.cpp
../../scripts/solution_test.sh submissions/accepted/sol.py
../../scripts/solution_test.sh submissions/accepted/sol.go
../../scripts/solution_test.sh submissions/accepted/sol.java

The script tests all cases in data/sample/ first, then data/secret/, and reports AC / WA / TLE per case. Exits non-zero if any case fails.

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Generating PDFs

Authors write Markdown in statement/problem.md. Run from inside the challenge directory:

cd challenges/<problem-id>
../../scripts/render-pdf.sh

Install once (Linux):

sudo apt install pandoc texlive-xetex texlive-fonts-recommended texlive-latex-extra

macOS:

brew install pandoc && brew install --cask basictex
sudo tlmgr update --self && sudo tlmgr install collection-xetex collection-latexextra

Windows: install Pandoc + MiKTeX (auto-downloads missing LaTeX packages on first run).

No local install needed? Push your .md — the GitHub Actions workflow renders the PDF automatically and uploads it as a downloadable artifact.