KMP pattern searching is an advanced algorithm & it is hard to explain it in simple terms. I stumbled on to this resource recently. I think it is a good starting point for people wanting to understand the basic idea about the KMP algorithm & its time complexity. It is without technical jargons & have concrete examples for understanding worst time complexity. So I thought of sharing with you. Please comment whether you find it useful or not especially for new learners.
This is also a good resource written by Galen Colin .
https://binary-baba.medium.com/string-matching-kmp-algorithm-27c182efa387