Add ScalesFitness method for Scales problem

[devin-ai-integration]

Summary

Implements the ScalesFitness method in Labs/ScalesProblem/ScalesSolver.java for the Scales problem.

Test #1 — Invalid input handling (returns -100):

• rep or weights is null
• rep or weights has size zero
• rep.size() is greater than weights.size()

Test NABBrunel#2 — Penalty regime (0, 0, 10, 20, ... %):
When rep.size() < weights.size(), unassigned weights incur a penalty:

• 0 unassigned → 0% penalty
• 1 unassigned → 0% penalty
• 2 unassigned → 10% penalty
• 3 unassigned → 20% penalty
• n unassigned (n ≥ 2) → (n−1) × 10% penalty, applied as a percentage of total weight added to the base fitness

Base fitness = |leftSum − rightSum| where true = left side, false = right side.

Review & Testing Checklist for Human

• Verify ScalesFitness returns -100 for null, empty, and oversized rep inputs
• Verify penalty regime matches the expected pattern (0, 0, 10, 20, ... %)
• Compile and run: javac ScalesSolver.java && java ScalesSolver

Notes

• A main method is included for quick manual testing of the function.

Link to Devin session: https://app.devin.ai/sessions/c5fd40e46d1f4ddba06784e61733b818
Requested by: @2431250

---

[devin-ai-integration]

🤖 Devin AI Engineer

I'll be helping with this pull request! Here's what you should know:

✅ I will automatically:

• Address comments on this PR. Add '(aside)' to your comment to have me ignore it.
• Look at CI failures and help fix them

Note: I can only respond to comments from users who have write access to this repository.

⚙️ Control Options:

• Disable automatic comment and CI monitoring

[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

View in Devin Review to see 2 additional findings.