Gattai-3 – Hard

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Gattai-3 Sudoku is a captivating variant of the classic Sudoku puzzle. It involves not one, but three interconnected 9x9 grids, providing a larger and more complex solving space. The challenge is to fill every row, column, and 3x3 box with the numbers 1 through 9 in such a way that each number appears once in each segment, adhering to the fundamental Sudoku rules, but across three overlapping grids.

Basic Rules

1. Number Range: Use numbers 1 through 9.
2. Grid Structure: The puzzle consists of three overlapping 9x9 grids.
3. Unique Numbers: Each number 1-9 must appear exactly once in each row, column, and 3x3 box.

Additional Rules

• Overlap Consistency: The overlapping regions between the grids must respect the Sudoku rules across the grids, meaning numbers should not repeat in rows, columns, and boxes even in the overlapping sections.

Basic Solving Tips

• Start with Certainties: Begin by filling in squares where a number is definitively determined by the existing numbers in the grid.
• Use Elimination: Identify which numbers cannot be in a particular square and eliminate them as possibilities for that square.
• Look for Grid Intersections: Pay special attention to the overlapping areas between the grids, as these can often provide additional clues or constraints that help to determine the placement of numbers.
• Row and Column Intersection: Often, a row or column from one grid will intersect with a box in another grid. Use this intersection to help determine which numbers are possible in that box.
• Persistence: Some squares may not be solvable initially. Keep moving and return to challenging spots after filling in more of the grid.