Coursera is really good. Introduction to Discrete Mathematics for Computer Science | Coursera https://www.coursera.org/specializations/discrete-mathematics http

Coursera is really good. Introduction to Discrete Mathematics for Computer Science | Coursera https://www.coursera.org/specializations/discrete-mathematics https://www.coursera.org/specializations/discrete-mathematic... Alexander Shen is one of the professors back in school his book helped me in stuff related to competitive programming.