洛谷: http://www.luogu.org/
图式工具: http://cs academy.com/app/graph _ editor
OIerDb: http://bytew.net/OIer/
博客园博客: https://www.cnblogs.com/Clever-温柔的白色/
OEIS: http://oeis.org/
床: http://sm.ms/
格式转换工具: https://cloudconvert.com/
3:3359 www.cn blogs.com/clever -转载于温柔大白/p/Useful_Tools.html