Optimize NFA Construction for Simple Patterns

[ofabiodev]

Current NFA construction overestimates spectral radius for simple patterns like a+ or [0-9]+, marking them unsafe. This update will:

• Detect simple vs nested loops correctly
• Adjust spectral radius calculation
• Apply DFA minimization to improve accuracy

⚠️ Impact:

Breaking change: patterns previously considered unsafe may now be safe. Users relying on old radius values might see different results.

⚙️ Proposed Implementation:

• Implement cycle detection for simple loops
• Modify spectral radius computation
• Apply DFA minimization after NFA construction

📝 Examples:

check("a+")       // before: unsafe, now: safe ✅
check("(a+)+")    // remains unsafe