solution week 251-2 -- Elixir

1 files changed, 70 insertions, 0 deletions

diff --git a/challenge-251/wambash/elixir/ch-2.exs b/challenge-251/wambash/elixir/ch-2.exs
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+defmodule LuckyNumber do
+  def lucky_number(matrix) do
+    mm = min_max(matrix)
+    if mm == max_min(matrix), do: mm, else: -1
+  end
+
+  def min_max(matrix) do
+    matrix
+    |> Stream.map(&Enum.min/1)
+    |> Enum.max()
+  end
+
+  def max_min(matrix) do
+    matrix
+    |> Stream.zip_with(&Enum.max/1)
+    |> Enum.min()
+  end
+end
+
+ExUnit.start()
+
+defmodule LuckyNumbersTest do
+  use ExUnit.Case
+
+  test "matrix 3x3" do
+    matrix = [
+      [3, 7, 8],
+      [9, 11, 13],
+      [15, 16, 17]
+    ]
+
+    assert LuckyNumber.min_max(matrix) == 15
+    assert LuckyNumber.max_min(matrix) == 15
+    assert LuckyNumber.lucky_number(matrix) == 15
+  end
+
+  test "matrix 4x4" do
+    matrix = [
+      [ 1, 10,  4,  2],
+      [ 9,  3,  8,  7],
+      [15, 16, 17, 12]
+    ]
+
+    assert LuckyNumber.min_max(matrix) == 12
+    assert LuckyNumber.max_min(matrix) == 12
+    assert LuckyNumber.lucky_number(matrix) == 12
+  end
+
+  test "matrix 2x2" do
+    matrix = [
+      [7, 8],
+      [1, 2]
+    ]
+
+    assert LuckyNumber.min_max(matrix) == 7
+    assert LuckyNumber.max_min(matrix) == 7
+    assert LuckyNumber.lucky_number(matrix) == 7
+  end
+
+  test "matrix 2x2 withou lucky number" do
+    matrix = [
+      [7, 2],
+      [1, 4]
+    ]
+
+    assert LuckyNumber.min_max(matrix) == 2
+    assert LuckyNumber.max_min(matrix) == 4
+    assert LuckyNumber.lucky_number(matrix) == -1
+  end
+end