Scaling Agentic Verifier for Competitive Coding

Fuente: arXiv
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Auteurs principaux: Ma, Zeyao, Zhang, Jing, Zhang, Xiaokang, Yang, Jiaxi, Zhang, Zongmeng, Zhang, Jiajun, Jing, Yuheng, Zhang, Lei, Zheng, Hao, Zhao, Wenting, Lin, Junyang, Hui, Binyuan
Format: Preprint
Publié: 2026
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author Ma, Zeyao
Zhang, Jing
Zhang, Xiaokang
Yang, Jiaxi
Zhang, Zongmeng
Zhang, Jiajun
Jing, Yuheng
Zhang, Lei
Zheng, Hao
Zhao, Wenting
Lin, Junyang
Hui, Binyuan
author_facet Ma, Zeyao
Zhang, Jing
Zhang, Xiaokang
Yang, Jiaxi
Zhang, Zongmeng
Zhang, Jiajun
Jing, Yuheng
Zhang, Lei
Zheng, Hao
Zhao, Wenting
Lin, Junyang
Hui, Binyuan
contents Large language models (LLMs) have demonstrated strong coding capabilities but still struggle to solve competitive programming problems correctly in a single attempt. Execution-based re-ranking offers a promising test-time scaling strategy, yet existing methods are constrained by either difficult test case generation or inefficient random input sampling. To address this limitation, we propose Agentic Verifier, an execution-based agent that actively reasons about program behaviors and searches for highly discriminative test inputs that expose behavioral discrepancies among candidate solutions. Through multi-turn interaction with code execution environments, the verifier iteratively refines the candidate input generator and produces targeted counterexamples rather than blindly sampling inputs. We train the verifier to acquire this discriminative input generation capability via a scalable pipeline combining large-scale data synthesis, rejection fine-tuning, and agentic reinforcement learning. Extensive experiments across five competitive programming benchmarks demonstrate consistent improvements over strong execution-based baselines, achieving up to +10-15% absolute gains in Best@K accuracy. Further analysis reveals clear test-time scaling behavior and highlights the verifier's broader potential beyond reranking.
format Preprint
id arxiv_https___arxiv_org_abs_2602_04254
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Scaling Agentic Verifier for Competitive Coding
Ma, Zeyao
Zhang, Jing
Zhang, Xiaokang
Yang, Jiaxi
Zhang, Zongmeng
Zhang, Jiajun
Jing, Yuheng
Zhang, Lei
Zheng, Hao
Zhao, Wenting
Lin, Junyang
Hui, Binyuan
Computation and Language
Large language models (LLMs) have demonstrated strong coding capabilities but still struggle to solve competitive programming problems correctly in a single attempt. Execution-based re-ranking offers a promising test-time scaling strategy, yet existing methods are constrained by either difficult test case generation or inefficient random input sampling. To address this limitation, we propose Agentic Verifier, an execution-based agent that actively reasons about program behaviors and searches for highly discriminative test inputs that expose behavioral discrepancies among candidate solutions. Through multi-turn interaction with code execution environments, the verifier iteratively refines the candidate input generator and produces targeted counterexamples rather than blindly sampling inputs. We train the verifier to acquire this discriminative input generation capability via a scalable pipeline combining large-scale data synthesis, rejection fine-tuning, and agentic reinforcement learning. Extensive experiments across five competitive programming benchmarks demonstrate consistent improvements over strong execution-based baselines, achieving up to +10-15% absolute gains in Best@K accuracy. Further analysis reveals clear test-time scaling behavior and highlights the verifier's broader potential beyond reranking.
title Scaling Agentic Verifier for Competitive Coding
topic Computation and Language
url https://arxiv.org/abs/2602.04254