Latest › Development

d Development ›Competitive Programming ·Tool · Added 3 days ago AI

AtCoder

atcoder.jp ↗

This page's summary, key points, and answers are generated by AI and may be inaccurate — always verify on the original source. How this works.

AtCoder is a premier competitive programming platform that hosts regular online contests for developers and students of all skill levels. It offers a variety of algorithm and heuristic challenges to help users improve their coding and problem-solving abilities.

Weekly competitive programming contests
Algorithm and heuristic challenge categories
Comprehensive global user ranking system
Archive of past contest problems

Who it's for: Best for students, software engineers, and programming enthusiasts looking to sharpen their algorithmic skills through competitive practice. AI

#programming28 #algorithms5 #contests2 #coding10 #software engineering10

Visit link ↗ Archived copy Explore graph Visualize

Overview AI

AtCoder provides a structured environment for programmers to test their skills against others globally through timed contests. Participants tackle algorithmic puzzles in categories like the Beginner Contest (ABC) or the Regular Contest (ARC). The platform maintains detailed rankings and a historical archive of problems, making it a valuable tool for both recreational coders and those preparing for technical interviews.

Gemini review AI

9/10

AtCoder manages to balance a high-pressure competitive environment with a genuinely inclusive community spirit. I find the consistent influx of fresh, high-quality problems to be the gold standard for those looking to stretch their algorithmic capabilities. While the interface is utilitarian and occasionally intimidating, it never gets in the way of the core experience. What impresses me most is the platform's commitment to both classic competitive programming and modern heuristic challenges. It is essential reading for anyone serious about mastering technical problem-solving.

Rated and reviewed by Gemini (gemini-3.1-flash-lite) from the page content at scan time — an AI-generated opinion, not a human review.

Pros & cons AI

Pros

Highly frequent, well-organized contest schedule
Excellent ranking system with global participation
Strong focus on both algorithm and heuristic challenges

Cons

High difficulty ceiling for newcomers
Interface can feel dense for first-time visitors

3 pros 2 cons

AtCoder vs LeetCode AI

AtCoder

atcoder.jp

LeetCode

leetcode.com

Choose AtCoder for pure competitive sport and high-level algorithmic growth, whereas LeetCode is optimized for interview preparation.

Aspect	AtCoder	LeetCode ↗
Primary Focus	Competitive programming contests	Technical interview preparation
Problem Style	Challenging, creative mathematical puzzles	Standard industry interview questions
Community Feel	Sports-like rankings and events	Professional career and hiring focus
Heuristic Challenges	Included as a core category	Not a primary focus
Learning Curve	Steeper for absolute beginners	Accessible with many guided tutorials

Questions & answers AI

Are the contests suitable for beginners?

Yes, AtCoder hosts specific Beginner Contests (ABC) designed for newcomers to competitive programming.

Does the site provide resources for study?

Users can access a deep archive of past problems and utilize the AtCoder Library to practice and study.

What's inside

Contest
Ranking: Algorithm
Ranking: Heuristic
Important announcements
Recent announcements
AtCoder Regular Contest 222 Announcement
CodeQUEEN 2026 -qual- (AtCoder Beginner Contest 462) Announcement
AtCoder Beginner Contest 461 Announcement
AtCoder Regular Contest++ 221 Announcement
AtCoder Beginner Contest 460 Announcement

Section headings detected on the page.

Page details

Original title: AtCoder
Original description: AtCoder is a programming contest site for anyone from beginners to experts. We hold weekly programming contests online.
Site: AtCoder
Author: AtCoder Inc.
Reading time: ~4 min · 839 words
Mobile-friendly: Yes
Indexable: Yes

Tech details

jQueryBootstrapGoogle Tag ManagerGoogle Analyticsnginx

Secure (HTTPS): Yes · HSTS
HTTP status: 200 OK
Server: nginx
Page size: 7 KB
Load time: 706 ms
Scanned: 2026-06-13 20:19:40

Performance · Google Lighthouse

Performance

Accessibility

Best practices

SEO

First Contentful Paint

3.9 s

Poor

Largest Contentful Paint

5.4 s

Poor

Total Blocking Time

51 ms

Good

Visual Stability (CLS)

0.00

Good

Lab data from Google Lighthouse via the PageSpeed Insights API (mobile) · tested Jun 13, 2026. Scores can vary between runs.

Alternatives & similar resources

Other resources that cover similar ground — and how they differ.

Explore related AI

Topics radiating out from this resource — click one to search the directory.

Data Structures Algorithmic Complexity Competitive Programming Software Engineering

AtCoder

AtCoder vs LeetCode AI

Alternatives & similar resources

Explore related AI

More in Development