AC Library is the official library of AtCoder. This repository manages the contents of AC Library.

You may refer to the following links for more details:

• The Announcement on AtCoder
• The Announcement on Codeforces
• Practice Contest
• AC Library Document(en)
• AC Library Document(ja)

Our goal of this project is to achieve that

• every AtCoder users can use this library with minimum efforts of studying about PC
• maximize convenience for the usage in competitive programming. We completely ignore other usages.
• no bugs. This is a fantasy, but we pursue this.

By this policy, we ignore some manners of C intentionally. For example,

• we don't use size_t, but use int.
• Segtree handles function pointers, not functional objects.
• and so on...

We haven't decided whether we should increase this library's contents or not because there are pros and cons. If you are interested in this topic, please join the discussion in The Announcement on Codeforces.

For now, we are not planning to add new features, and we use this repository only for

• collecting issues
• recording the changelogs
• versioning our releases

We accept issues/PRs only from AtCoder users.

We would appreciate it if you would report our mistakes like a typo, or, more importantly, bugs!

As mentioned above, we haven't decided which way to go. Therefore we close feature requests for now.

You can view the newest version of AC Library in The Announcement on AtCoder page.

You can also see all versions in The Release page.

• The header files in atcoder folder are licensed under a CC0 license.
• TODO: We haven't determined the license of other files.