I'm stuck while working with rewrites,
The structure I'm trying to achieve is this:

1) https://example.com/blog/${post-name} -- For regular blog posts
eg: https://example.com/my-blog-post-1

2) https://example.com/${custom-post-name-slug} -- For custom post type
eg: https://example.com/book1, https://example.com/book2

3) https://example.com/${custom-post-name-parent-slug}/${custom-post-name-child-slug} -- For custom post type child page
eg: https://example.com/book1/critics, https://example.com/book2/critics