Killer Sudoku Pro

Professional-grade Killer Sudoku with 3 difficulty tiers. Algorithmic puzzle generation ensures unique, solvable challenges every time.

Killer Sudoku represents the evolution of classic number puzzles. This implementation delivers a professional-grade experience with rigorous validation and optimized puzzle generation.

TECHNICAL SPECIFICATIONS: • 9×9 grid with standard Sudoku constraints (row/column/box uniqueness) • Cage partitioning algorithm generates 15-35 cages per puzzle • Target sum constraints with intra-cage non-repetition rule • Three calibrated difficulty tiers:

• Easy: 1-3 cell cages, 12 given cells
• Medium: 1-4 cell cages, 6 given cells
• Hard: 1-5 cell cages, 0 given cells (pure deduction)

VALIDATION ENGINE: Real-time conflict detection monitors: • Row duplicates (horizontal constraint) • Column duplicates (vertical constraint) • Box duplicates (3×3 region constraint) • Cage duplicates (intra-cage uniqueness) • Cage sum overflow (partial sum exceeds target) • Cage sum mismatch (completed cage sum ≠ target)

PERFORMANCE METRICS: • Puzzle generation: under 2 seconds (optimized backtracking algorithm) • Auto-save: 500ms debounced writes to UserDefaults • Undo stack: 100-step history with O(1) rollback • Timer resolution: 1-second precision with pause/resume

USER INTERFACE DESIGN: • Dashed cage boundaries with 2pt inset rendering • Head cell displays target sum (smallest index in cage) • Cage completion state: green overlay for correct sums • Related cell highlighting (same row/column/box) • Cage highlighting (all cells in selected cage) • Note mode: 3×3 candidate grid per cell

ALGORITHMIC GUARANTEES: • Every puzzle has exactly one valid solution • Cage partitioning ensures logical solvability • No guesswork required—pure deductive reasoning

Optimized for iOS 16+. 100% offline operation. Zero network dependencies.