Puzzle struct that maps cell IDs to cell values.

IDs of all cells on a Sudoku grid.

Get value of cell at cell_id in the puzzle.

Returns :_ (unoccupied) if no value associated with the cell_id.

Empty cells in the puzzle.

Returns whether puzzle has a numerical value in every cell.

Examples

iex> %Puzzle{cells: %{{0, 0} => 1}}
...> |> Puzzle.filled_in?
false

iex> %Puzzle{
...>   cells: Puzzle.cell_ids
...>          |> Enum.map(&({&1, 9}))
...>          |> Enum.into(%{})
...> } |> Puzzle.filled_in?
true

Create Puzzle from list of lists of cell values.

Examples

A puzzle copied from Wikipedia.

iex> Puzzle.from_list([
...> [5,   3, :_, :_,  7, :_, :_, :_, :_],
...> [6,  :_, :_,  1,  9,  5, :_, :_, :_],
...> [:_,  9,  8, :_, :_, :_, :_,  6, :_],
...> [8,  :_, :_, :_,  6, :_, :_, :_,  3],
...> [4,  :_, :_,  8, :_,  3, :_, :_,  1],
...> [7,  :_, :_, :_,  2, :_, :_, :_,  6],
...> [:_,  6, :_, :_, :_, :_,  2,  8, :_],
...> [:_, :_, :_,  4,  1,  9, :_, :_,  5],
...> [:_, :_, :_, :_,  8, :_, :_,  7,  9],
...> ])
{:ok, %Puzzle{
  cells: %{
    {0, 0} => 5, {0, 1} => 3, {0, 4} => 7,
    {1, 0} => 6, {1, 3} => 1, {1, 4} => 9, {1, 5} => 5,
    {2, 1} => 9, {2, 2} => 8, {2, 7} => 6,
    {3, 0} => 8, {3, 4} => 6, {3, 8} => 3,
    {4, 0} => 4, {4, 3} => 8, {4, 5} => 3, {4, 8} => 1,
    {5, 0} => 7, {5, 4} => 2, {5, 8} => 6,
    {6, 1} => 6, {6, 6} => 2, {6, 7} => 8,
    {7, 3} => 4, {7, 4} => 1, {7, 5} => 9, {7, 8} => 5,
    {8, 4} => 8, {8, 7} => 7, {8, 8} => 9}}}

Copy of puzzle where cell_value is associated with cell_id.

9-cell rows, columns, and sectors on the puzzle grid.

Each region must have no repeated cell values. See valid?.

Returns whether puzzle is in a solved state.

A Sudoku puzzle is said to be solved if it is both filled_in? and valid?.

Examples

iex> {:ok, puzzle} = Puzzle.from_list([
...>   [5, 3, 4, 6, 7, 8, 9, 1, 2],
...>   [6, 7, 2, 1, 9, 5, 3, 4, 8],
...>   [1, 9, 8, 3, 4, 2, 5, 6, 7],
...>   [8, 5, 9, 7, 6, 1, 4, 2, 3],
...>   [4, 2, 6, 8, 5, 3, 7, 9, 1],
...>   [7, 1, 3, 9, 2, 4, 8, 5, 6],
...>   [9, 6, 1, 5, 3, 7, 2, 8, 4],
...>   [2, 8, 7, 4, 1, 9, 6, 3, 5],
...>   [3, 4, 5, 2, 8, 6, 1, 7, 9]])
iex> {puzzle |> Puzzle.solved?,
...>  puzzle |> Puzzle.put_cell({0, 0}, 1) |> Puzzle.solved?}
{true, false}

Returns whether puzzle is valid.

Each of puzzle’s 81 cells must be occupied by a number from 1-9, inclusive, or the :_ atom which means “unoccupied”. Cells with no value are implictly :_.

Additionally, no individual row, column, nor sector may have repeated cell number values. Sectors are the puzzle’s nine 3x3 sub-grids.

Examples

iex> %Puzzle{cells: %{{0, 0} => 1}}
...> |> Puzzle.valid?
true

iex> %Puzzle{cells: %{{0, 0} => 1, {0, 7} => 1}}
...> |> Puzzle.valid?
false