crypto-square

elixir/crypto-square/lib/crypto_square.ex

@@ -19,13 +19,17 @@ defmodule CryptoSquare do
     |> String.replace(~r/[^a-z0-9]/, "")
   end
 
+  defp square(""), do: ""
+
   defp square(str) do
     length = String.length(str)
-    row = :math.ceil(length ** 0.5)
+    row = round(ceil(length ** 0.5))
-    col = :math.ceil(length / row)
 
     str
     |> String.split("", trim: true)
-    |> Enum.chunk_every(col, col)
+    |> Enum.chunk_every(row, row, List.duplicate(" ", row))
+    |> Enum.zip()
+    |> Enum.map(&Tuple.to_list(&1))
+    |> Enum.map_join(" ", &Enum.join(&1))
   end
 end

elixir/crypto-square/test/crypto_square_test.exs

@@ -1,42 +1,34 @@
 defmodule CryptoSquareTest do
   use ExUnit.Case
 
-  # @tag :pending
   test "empty plaintext results in an empty ciphertext" do
     assert CryptoSquare.encode("") == ""
   end
 
-  @tag :pending
   test "normalization results in empty plaintext" do
     assert CryptoSquare.encode("... --- ...") == ""
   end
 
-  @tag :pending
   test "lowercase" do
     assert CryptoSquare.encode("A") == "a"
   end
 
-  @tag :pending
   test "remove spaces" do
     assert CryptoSquare.encode("  b ") == "b"
   end
 
-  @tag :pending
   test "remove punctuation" do
     assert CryptoSquare.encode("@1,%!") == "1"
   end
 
-  @tag :pending
   test "9 character plaintext results in 3 chunks of 3 characters" do
     assert CryptoSquare.encode("This is fun!") == "tsf hiu isn"
   end
 
-  @tag :pending
   test "8 character plaintext results in 3 chunks, the last one with a trailing space" do
     assert CryptoSquare.encode("Chill out.") == "clu hlt io "
   end
 
-  @tag :pending
   test "54 character plaintext results in 7 chunks, the last two with trailing spaces" do
     msg = "If man was meant to stay on the ground, god would have given us roots."
     cipher = "imtgdvs fearwer mayoogo anouuio ntnnlvt wttddes aohghn  sseoau "