However, if you are looking to solve interesting problems during holidays/spare time see this book.

Here is a small list of some of the problems I will encourage you to try: exercises 6.15, or 7.13 (to be done without arrays), 8.9, 10.12, 10.18, 14.20, 16.6, 16.9 (to solve any cryptarithm), 19.2.

In addition the book gives many suggestions for projects involving games, simulations, physics, and algorithms. See exercises 5.10, 19.3, 20.1-3, 22.11, 23.4, 23.5, 24.6-14, 26.1-2, 26.3, 27.4, 27.7, 29.3.

The library simplecpp provides support for elementary graphics and animation and will be useful in projects.