Discrete mathematics exercises (in greek)
The following three sets are selected exercises (and their solutions) on generating functions from the third chapter of the book "An introduction to the analysis of algorithms" by Philippe Flajolet and Robert Sedgewick.
Set1 Set2 Set3
Approximation algorithms exercises (in greek)
Selected exercises and solutions on approximation algorithms, mostly from the the book "Approximation Algorithms" by Vijay V. Vazirani.
Cryptography exercises (in greek)
Two sets of exercises and solutions on cryptography and related mathematics. A great introductory tutorial on cryptography is the 31st chapter from the book "Introduction to Algorithms", Second edition, by Thomas Cormen, Charles Leiserson, Ronald Rivest and Clifford Stein.