computer science

https://deadlockempire.github.io/

https://web.mit.edu/mprat/Public/web/Terminus/Web/main.html

https://overthewire.org/wargames/

catalan number

https://www.distributedsystemscourse.com/

https://textbook.cs161.org/

cs162

cs164

https://www.youtube.com/watch?v=X8jsijhllIA&t=0s

https://www.youtube.com/watch?v=5sskbSvha9M

https://youtube.com/playlist?list=PLiwt1iVUib9s2Uo5BeYmwkDFUh70fJPxX

https://teachyourselfcs.com/

http://web.mit.edu/6.033/www/index.shtml

https://eater.net/inet

https://missing.csail.mit.edu/

https://www.youtube.com/watch?v=WDIkqP4JbkE

https://www.youtube.com/watch?v=TtiBhktB4Qg&list=PL0M0zPgJ3HSesuPIObeUVQNbKqlw5U2Vr

https://www.youtube.com/watch?v=tpIctyqH29Q&list=PL8dPuuaLjXtNlUrzyH5r6jN9ulIgZBpdo

https://pdos.csail.mit.edu/6.824/schedule.html

https://inst.eecs.berkeley.edu/~cs61c/su20/

https://15445.courses.cs.cmu.edu/fall2019/schedule.html

https://www.youtube.com/watch?v=UEAMfLPZZhE&list=PLeKd45zvjcDFUEv_ohr_HdUFe97RItdiB

https://www.youtube.com/playlist?list=PL0M0zPgJ3HSesuPIObeUVQNbKqlw5U2Vr

https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-006-introduction-to-algorithms-spring-2020/

https://www.youtube.com/watch?v=qAFI-2I7wPE&list=PLoCMsyE1cvdWKsLVyf6cPwCLDIZnOj0NS

https://www.educative.io/courses/operating-systems-virtualization-concurrency-persistence

https://pages.cs.wisc.edu/~remzi/OSTEP/

Math

http://discrete.openmathbooks.org/dmoi3/dmoi.html

https://docviewer.yandex.uz/view/595338447/?*=uMaqPPxQ0jnNVqCzgW6IkCoz4j97InVybCI6InlhLWRpc2s6Ly8vZGlzay9Cb29rcy9Db21wdXRlciBTY2llbmNlL01hdGgvZG1ib29rLnBkZiIsInRpdGxlIjoiZG1ib29rLnBkZiIsIm5vaWZyYW1lIjpmYWxzZSwidWlkIjoiNTk1MzM4NDQ3IiwidHMiOjE2MzUzMzAzODY4MzIsInl1IjoiMzg5ODU2NDY0MTU5MjkxMjk0OCJ9

http://gaia.cs.umass.edu/kurose_ross/lectures.php

The Basics - YouTube

https://www.youtube.com/playlist?list=PL96C35uN7xGLLeET0dOWaKHkAlPsrkcha

https://www.youtube.com/watch?v=dNRDvLACg5Q&list=PLzH6n4zXuckrEzV0CB1xXbSdsP_a7VUoK&index=2