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ALE-Bench provides AtCoder Heuristic Contest problems for evaluating algorithmic optimization agents. Kapso achieved #1 on ALE-Bench.
ALE-Bench bar chart: Kapso's final rating of 1909 Elo against ALE Agent's 1879, above a per-problem breakdown of ten AtCoder Heuristic Contest problems; every row is drawn from its own truncated Elo origin, and the per-problem bar gaps share one scale

Elo rating per AtCoder Heuristic Contest problem, against ALE Agent

Usage

CLI options

Scored problems

The reported result covers these ten problems; --lite lists the full 13-problem lite roster and --list every ALE-Bench problem: ahc008, ahc011, ahc015, ahc016, ahc024, ahc025, ahc026, ahc027, ahc039, ahc046
Both modes run the generic search strategy, but the ALE handler supplies the official evaluation: solutions are scored by the ALE-Bench toolkit via handler.run() rather than agent-built evaluation.

Output structure

The agent generates:

Evaluation

The evaluation process works as follows:
  1. Code Submission: The main.cpp file is read from the experiment workspace
  2. Docker Evaluation: Code is sent to ale_bench.public_eval() which compiles and runs in an isolated Docker container
  3. Test Execution: Solution runs against all test cases with strict time limits
  4. Validation: Each test case must return ACCEPTED with a non-zero score
  5. Score Stabilization: If all tests pass, the solution runs 4 times in total (3 further runs) and scores are averaged for stability
  6. Final Ranking: Private evaluation compares against original contest participants

Code requirements

Generated C++ must:
  • Be time-aware (limit: time_limit - 100ms for I/O)
  • Handle all input constraints
  • Use efficient algorithms and data structures
  • Include compiler optimization pragmas if helpful

Built-in domain knowledge

The handler includes tips for common algorithms:
  • Design good state representation
  • Balance small and large moves
  • Avoid recomputation in legality checks
  • Keep regret mechanism for constrained problems
  • Balance diversity and quality in beams
  • Fast-stop bad solutions
  • Use strong heuristic scoring
  • Define strong heuristic scoring
  • Consider average and std of scores
  • Balance greedy vs long-horizon moves

Installation

Installing the harness

IOAI 2026

The olympiad track
Related pages: Installation · IOAI 2026 · IOAI 2026 Kapso is an open-source framework by Leeroo that builds software toward measurable goals through experiment campaigns. Source code: github.com/Leeroo-AI/kapso · Install: pip install leeroo-kapso · Every page as plain text: llms.txt.