A description is incomplete. It should mention:

These patterns are not competing, but complementing each other. To achieve availability, one needs both fail-over and replication.

right after

"There are two main patterns to support high availability: fail-over and replication. "

• We have BFS and DFS images in both Breadth First Traversal and Depth First Traversal. We should have illustrations in the respective sections.

https://mybinder.org/ Should I make a binder ? :) Or if there is a binder link, it's well hidden.

Each solution should have a comment stating the time (and maybe the space) complexity of the solution