Chapter 1 is the toolbox: the data structures that every problem in the plan is built on. Each chapter after it is one topic of Top Interview 150, in the same order, with the idea, the code and the cost of every solution. Every example is in C, so nothing is hidden in a magic box: you see every allocation, pointer and copy.
Want to watch the structures move? See jrzayev/dsa-visual-c, colorful terminal animations in C.