Project Euler *www.projecteuler.net/.. nfff said ..
Try the problems here .. if you like computing or programming then this will be enough for the next 25-30 days..
Learn Algorithims and their working MIT OP
This will really help you out.
If you have programmed or can build c++ or c programs then you don't need classes but few good books and some dedication thats all.
For C : The C programming Language. By Brian W. Kernighan and Dennis M. Ritchie. ( Its a must buy )
The C Programming Language: Ansi C Version 2 Edition - Buy The C Programming Language: Ansi C Version 2 Edition by Kernighan, Brian W.|Author; Ritchie, Dennis M.|Author; Online at Best Prices in India - Flipkart.com
C++ you can try "C++ from the ground up" Buy C++ from the Ground Up by Herbert Schildt, Schildt Herbert, Michael Mueller, C++ from the Ground Up Book Reviews, Buy Book Online- Infibeam.com
All the best.. But remember there are no shortcuts ... you'll have to sit and code and code away.