I dont know if author is reading it or not. but u starting two questions with the problems which are categorized as hard in leetcode and requires high thinking. you should start with easy and medium problems like you did in the previous version of course
Course: Grokking Coding Interview Patterns in Python - Learn Interactively
Lesson: https://www.educative.io/courses/grokking-coding-interview-patterns-python/3wNEnrZ2qRA