HiPO: Hybrid Policy Optimization for Dynamic Reasoning in LLMs. - Ken Deng; Zizheng Zhan; Wen Xiang; Wenqiang Zhu; Tianhao Peng; Xinping Lei; Weihao Li; Jingxuan Xu; Kun Wu; Yifan Yao; Haoyang Huang; Huaixi Tang; et al. (CoRR, 2025)