资源

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Online Judge

Luogu | Codeforces | BZOJ | AtCoder | Nowcoder

UOJ | LOJ | HDU | POJ | Project Euler

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Tools

GitHub | OI Wiki | OIerDb | Ubuntu Pastebin | CF-Predictor

Google Sytle Guide | OEIS | WolframAlpha | Graph Editor | Waifu2x