Here are some top resources for CPO problems in PDF format:
, you’re essentially preparing for the "Final Boss" of high school physics. Known globally for its extreme difficulty—often surpassing the International Physics Olympiad (IPhO)—CPhO problems are legendary for their mathematical rigor and complex multi-stage modeling.
The most valuable PDF is a scanned, annotated collection of past Semifinal and Final exams (2000–present). These are often in Chinese, but the equations are universal. Look for files with "全国中学生物理竞赛" and "复赛试题". The "top" versions include official solutions, which are masterclasses in concise, elegant reasoning.
This stage marks a major jump in difficulty. Problems require single-variable calculus, differential equations, and complex multi-stage modeling. Final Round / Winter Camp (决赛)