I am writing a series of books on computer science which will be heavy on algorithms and AI . I wanted to use CodeChef problems in my book as practice problems . I want to know what is the permission level required if :

- I have to give a link to a CodeChef problem.
- I have to give a link to a CodeChef problem and reproduce the problem statement (possibly modified for clarity if i feel its needed).
- I have to give a link to a CodeChef problem and reproduce the problem statement and also give a solution explaining how to solve it.
- I have to give a link to CodeChef problem and a link to some user’s solution as a model solution.
- I have to give a link to CodeChef problem and its editorial.
- Make a quote from the CodeChef problem editorial .

What will be the permission level required for each of the above things ? Like :

a. No permission needed .

b. CodeChef trademark and logo has to be reproduced.

c. Written permission is needed.

d. Permission of user whose solution is referred is needed.

e. Payment is needed.

f. Permission can’t be granted.

Please let me know the needful.

Also , would like to know if CodeChef would like to be a publisher for my books . I have just begun on this project. I am an employee of Directi, but this is a personal project that i do in free time.