diff --git a/lib/transport.rb b/lib/transport.rb
index d930638..8af138e 100644
--- a/lib/transport.rb
+++ b/lib/transport.rb
@@ -1,11 +1,11 @@
+# 文字列で表現された行列を転置して、文字列形式で返す
+# ex) 入力: "1 2 3\n4 5 6\n7 8 9\n10 11 12"
+#     出力: "1 4 7 10\n2 5 8 11\n3 6 9 12"
 def transport(source)
-  array = source.split("\n").map {|s| s.split(" ")}
-  rows_count = array.first.count
-
-  transported_array = []
-  0.upto(rows_count - 1) do |i|
-    transported_array << array.map {|a| a[i]}
-  end
-
-  transported_array.map {|s| s.join(" ")}.join("\n")
+  source
+      .split("\n")
+      .map {|s| s.split(" ")}
+      .transpose
+      .map {|a| a.join(" ")}
+      .join("\n")
 end
\ No newline at end of file
diff --git a/test/transport_test.rb b/test/transport_test.rb
index 64126c8..22af2ce 100644
--- a/test/transport_test.rb
+++ b/test/transport_test.rb
@@ -3,12 +3,29 @@
 
 class TransportTest < MiniTest::Test
   def test_transport
-    input = "1 2 3\n4 5 6\n7 8 9"
-    output = "1 4 7\n2 5 8\n3 6 9"
-    assert_equal output, transport(input)
+    input = <<~EOS.chomp
+      1 2 3
+      4 5 6
+      7 8 9
+    EOS
+    expect = <<~EOS.chomp
+      1 4 7
+      2 5 8
+      3 6 9
+    EOS
+    assert_equal expect, transport(input)
 
-    input = "1 2 3\n4 5 6\n7 8 9\n10 11 12"
-    output = "1 4 7 10\n2 5 8 11\n3 6 9 12"
-    assert_equal output, transport(input)
+    input = <<~EOS.chomp
+      1 2 3
+      4 5 6
+      7 8 9
+      10 11 12
+    EOS
+    expect = <<~EOS.chomp
+      1 4 7 10
+      2 5 8 11
+      3 6 9 12
+    EOS
+    assert_equal expect, transport(input)
   end
 end
\ No newline at end of file