Practice problems
Links for practice websites
- Labatt Contest Problems
- UVa Online Judge
- Sphere Online Judge
- ACM ICPC Programming Problems
- Collegiate Programming Exam
Online Judges
Europe
- Valladolid Online Judge (Spain)
- Saratov State University (Russia)
- Timus Online Judge (Russia)
- Sphere Online Judge (Poland)
- High School Programming League (Poland)