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  2. Mathematics of Sudoku - Wikipedia

    en.wikipedia.org/wiki/Mathematics_of_Sudoku

    Mathematical context. The general problem of solving Sudoku puzzles on n2 × n2 grids of n × n blocks is known to be NP-complete. [8] A puzzle can be expressed as a graph coloring problem. [9] The aim is to construct a 9-coloring of a particular graph, given a partial 9-coloring. The Sudoku graph has 81 vertices, one vertex for each cell.

  3. Sudoku - Wikipedia

    en.wikipedia.org/wiki/Sudoku

    A Sudoku with 18 clues and two-way diagonal symmetry. This section refers to classic Sudoku, disregarding jigsaw, hyper, and other variants. A completed Sudoku grid is a special type of Latin square with the additional property of no repeated values in any of the nine blocks (or boxes of 3×3 cells).

  4. Eight queens puzzle - Wikipedia

    en.wikipedia.org/wiki/Eight_queens_puzzle

    Eight queens puzzle. The eight queens puzzle is the problem of placing eight chess queens on an 8×8 chessboard so that no two queens threaten each other; thus, a solution requires that no two queens share the same row, column, or diagonal. There are 92 solutions. The problem was first posed in the mid-19th century.

  5. Crossword - Wikipedia

    en.wikipedia.org/wiki/Crossword

    An American-style crossword grid layout. A crossword (or crossword puzzle) is a word game consisting of a grid of black and white squares, into which solvers enter words or phrases ("entries") crossing each other horizontally ("across") and vertically ("down") according to a set of clues. Each white square is typically filled with one letter ...

  6. Nine dots puzzle - Wikipedia

    en.wikipedia.org/wiki/Nine_dots_puzzle

    The "nine dots" puzzle. The puzzle asks to link all nine dots using four straight lines or fewer, without lifting the pen. The nine dots puzzle is a mathematical puzzle whose task is to connect nine squarely arranged points with a pen by four (or fewer) straight lines without lifting the pen. The puzzle has appeared under various other names ...

  7. Wheat and chessboard problem - Wikipedia

    en.wikipedia.org/wiki/Wheat_and_chessboard_problem

    The problem may be solved using simple addition. With 64 squares on a chessboard, if the number of grains doubles on successive squares, then the sum of grains on all 64 squares is: 1 + 2 + 4 + 8 + ... and so forth for the 64 squares. The total number of grains can be shown to be 2 64 −1 or 18,446,744,073,709,551,615 (eighteen quintillion ...

  8. Missing square puzzle - Wikipedia

    en.wikipedia.org/wiki/Missing_square_puzzle

    Animation of the missing square puzzle, showing the two arrangements of the pieces and the "missing" square Both "total triangles" are in a perfect 13×5 grid; and both the "component triangles", the blue in a 5×2 grid and the red in an 8×3 grid.

  9. Rubik's Cube - Wikipedia

    en.wikipedia.org/wiki/Rubik's_Cube

    The Rubik's Cube is a 3D combination puzzle invented in 1974 [2][3] by Hungarian sculptor and professor of architecture Ernő Rubik. Originally called the Magic Cube, [4] the puzzle was licensed by Rubik to be sold by Pentangle Puzzles in the UK in 1978, [5] and then by Ideal Toy Corp in 1980 [6] via businessman Tibor Laczi and Seven Towns ...