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Contents
defmodule Minesweeper do
@doc """
Annotate empty spots next to mines with the number of mines next to them.
"""
@spec annotate([String.t()]) :: [String.t()]
def annotate([]), do: []
def annotate(board) do
h = length(board)
# Only 7-bit ASCII in the board, so this is safe
w = String.length(hd(board))
annotations =
Enum.reduce(Stream.with_index(board), %{}, fn {line, y}, acc ->
Enum.reduce(Stream.with_index(String.to_charlist(line)), acc, fn
{?*, x}, acc -> add_adjacents(acc, {x, y}, {w, h})
_, acc -> acc
end)
end)
Enum.map(Stream.with_index(board), fn {line, y} ->
Enum.map(Stream.with_index(String.to_charlist(line)), fn
# Don't replace mines
{?*, _} ->
?*
{_, x} ->
case annotations[{x, y}] do
nil -> ?\s
n -> ?0 + n
end
end)
|> to_string
end)
end
@adjacent_vecs for x <- [-1, 0, 1],
y <- [-1, 0, 1],
x != 0 or y != 0,
do: {x, y}
defp add_adjacents(d, c, bounds) do
Enum.reduce(@adjacent_vecs, d, fn v, acc ->
c1 = add_vec(c, v)
if valid?(c1, bounds) do
Map.update(acc, c1, 1, &(&1 + 1))
else
acc
end
end)
end
defp add_vec({cx, cy}, {vx, vy}), do: {cx + vx, cy + vy}
defp valid?({cx, cy}, {w, h}), do: cx >= 0 and cx < w and cy >= 0 and cy < h
end
Version data entries
131 entries across 131 versions & 1 rubygems