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Create New Problem (new_problem)

Status: Informational
Scope: Creating solution skeleton files in solutions/ via scripts/new_problem.bat / scripts/new_problem.sh
Last Updated: January 4, 2026 15:11:06
Created: January 3, 2026 21:02:34

scripts/new_problem.bat / scripts/new_problem.sh are thin wrappers around CodeGen:

  • They run python -m codegen new ...
  • They forward all arguments as-is
  • They return the same exit code as CodeGen

When to use this

Use this when you want to create a new reference solution skeleton for a LeetCode problem:

  • Output directory: solutions/
  • Output filename format: <id:04d>_<slug>.py (example: 0001_two_sum.py)

If the solution file already exists, CodeGen will refuse to overwrite (unless you delete it and regenerate).

Usage

Run from the repository root.

Windows

.\scripts\new_problem.bat <problem_id> [options]

Linux / macOS

./scripts/new_problem.sh <problem_id> [options]

Equivalent direct command (same behavior)

python -m codegen new <problem_id> [options]

Parameters

Required

  • problem_id (int): LeetCode problem number (frontend id), e.g. 1

Optional flags

  • --with-tests: Generate .in/.out test files from LeetCode examples (under tests/).
  • --force: Overwrite existing test files (only applies with --with-tests).
  • --dry-run: Print generated content to stdout and do not write files.
  • --solve-mode {placeholder,infer,tiered}:
  • placeholder: TODO-style solve()
  • infer: auto-generate solve() based on inferred I/O schema
  • tiered: config-based Tier-1 / Tier-1.5 solve() generation (codec-based)
  • --codec-mode {import,inline}: Override codec emission strategy for tiered solve generation (default: from config/problem-support.yaml)
  • --header-level {minimal,standard,full}: Controls the amount of problem header content (default: full)

Tiered auto-detection (Tier-1 / Tier-1.5)

Even if you do not pass --solve-mode tiered, CodeGen will auto-use tiered solve generation when the problem is marked as Tier "1" or "1.5" in:

  • config/problem-support.yaml

This is what enables correct handling for structures like ListNode / TreeNode / cycles via the codec layer.

Codec mode (import vs inline)

Tiered generation supports two codec emission strategies:

  • import: solve() imports codec utilities from runner.utils.codec
  • inline: codec utilities are embedded into the generated solution file

Default behavior is controlled by problem config (codec_mode in config/problem-support.yaml). You can override it for a single run via --codec-mode.

Examples

Generate a new solution skeleton:

.\scripts\new_problem.bat 1

Generate solution skeleton + LeetCode example tests:

.\scripts\new_problem.bat 1 --with-tests

Generate with auto-inferred solve():

.\scripts\new_problem.bat 1 --solve-mode infer

Preview without writing:

.\scripts\new_problem.bat 1 --with-tests --dry-run