3D Sudoku

Imagine instead of a two dimensional grid, we are now filling a 3D grid made up of nxnxn unit cubes with numbers 1 to n such that every row, column, and depth has exactly one of each number.

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Triangles in a Square

This problem is inspired by this geometry puzzle on Twitter. The original problem asks to find the ratio between two equilateral triangles fitted into a square.  Let’s generalize it.

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Variants of Sudoku

Today let’s explore one of the deviations from the standard sudoku rules that every row, column, and subgrid (excluded so we can generalize to non-perfect-square side lengths) must have exactly one of each number from 1 to n, where n is the side length of the sudoku puzzle.  Let’s include the new rule that a valid solution to a sudoku puzzle must also have one of each number in each of its two diagonals.

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Square Gluing Topology

Now let’s consider the surfaces we obtain by stretching and gluing the sides of a square together.

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Mini Sudoku

Sudoku is a one-player game where the player tries to fill the spaces of an nxn grid using numbers 1 to n, where n is a natural number, such that every column and every row contains exactly one of each number.

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Numbers of Polycubes

Let’s define polycubes as three dimensional shapes made up of unit cubes connected by shared faces.

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Tiling with Polynominoes

Let’s consider tiling square grids using polynominoes of any number of units.

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Perimeters of Polynominoes

If we separate all tetrominoes according to their perimeters, we would have two groups.

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Symmetry of Polynominoes

Polynominoes are figures made up of square units connected by edges.

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Tiling with Tetrominoes

Let’s consider tiling square grids with tetrominoes.  Pieces can be rotated, reflected, and repeated as needed.

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