HARDTESTGEN: A High-Quality RL Verifier Generation Pipeline for LLM Algorithimic Coding - He, Zhongmou; Choi, Yee Man; Zhang, Kexun; Bercovich, Ivan; Ji, Jiabao; Zhou, Junting; Xu, Dejia; Zhang, Aidan; Zeng, Yixiao; Li, Lei (International Conference on Learning Representations, 2026)