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Contents
defmodule Spiral do
@doc """
Given the dimension, return a square matrix of numbers in clockwise spiral order.
"""
@spec matrix(dimension :: integer) :: list(list(integer))
def matrix(0), do: []
def matrix(dimension) do
unwind(dimension, dimension, 1)
end
defp unwind(row, col, start) do
case col do
0 ->
[[]]
_ ->
[
Enum.to_list(start..(start + col - 1))
| unwind(col, row - 1, start + col) |> rotate_right
]
end
end
defp rotate_right(matrix) do
matrix |> transpose |> Enum.map(&Enum.reverse/1)
end
defp transpose(matrix) do
matrix |> List.zip() |> Enum.map(&Tuple.to_list/1)
end
end
Version data entries
69 entries across 69 versions & 1 rubygems