A lot of content will come from LinkedIn Learning (formerly Lynda.com). The Lynda training company has more than two decades experience creating high quality technical training for professionals. We will use these materials for two reasons, firstly, the material is professional-level by experts in the field and goes through quite a bit more checks and balances vs the random person on YouTube. Second, if you complete enough of a video series on LinkedIn Learning, you'll also get a certificate of completion.
LinkedIn Learning is fairly expensive... but... it's free with a Harris County and Houston Public Library Card.
To start with, let's get a bit of review on the concept of Algorithms.
Watch the 1. Overview sections of Programming Foundations: Algorithms from LinkedIn Learning.
^^^ The videos here are in Python, but we aren't going to use Python.
You should be able to more or less understand simple Python programs, even though we aren't using it.
Other videos are in JavaScript or other languages.
Once you understand the basic setups of programming languages, you can often more or less read simple programs in most languages.
You'll get there if you aren't already there.
When we actually program, we'll play with C=based languages.
Watch the following videos to better understand the concept of Big O...
You can try the tool he shows in the video here:
Explain the concept of Big O