Light Up – Hard

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Light Up, also known by other names such as "Akari" or "Bijutsukan," is a logic puzzle that involves illuminating a grid by strategically placing light bulbs. The grid consists of white and black cells, where light bulbs are placed in the white cells under certain rules to ensure the entire grid is lit up without any two bulbs shining on each other.

Basic Rules

1. Light Bulbs Placement: Light bulbs are placed in white cells.
2. Illumination: A light bulb illuminates its entire row and column unless blocked by a black cell.
3. No Overlapping Rays: No two bulbs should shine on each other, meaning bulbs cannot be placed in the same row or column without a black cell between them.
4. Black Cell Numbers: A black cell may contain a number (0-4), indicating how many bulbs must be adjacent to it.

Additional Rules

• Unnumbered Black Cells: Black cells without numbers can have any number of bulbs adjacent to them or none.
• Diagonal Placement: Bulbs placed diagonally adjacent to a numbered cell do not contribute to the bulb count.

Basic Solving Tips

1. Start with Defined Black Cells: Begin by placing bulbs around black cells with numbers, adhering to the specified count.
2. Avoid Bulb Clashes: Ensure that the light rays from any two bulbs do not intersect.
3. Maximize Illumination: Try to place bulbs in positions that illuminate the most number of white cells.
4. Check for Shadows: Ensure all white cells are illuminated and adjust bulb placements to avoid any dark (unlit) cells.