ls

ls.rb

@@ -0,0 +1,56 @@
+# frozen_string_literal: true
+
+items = []
+
+NUM_COLUMNS = 3 # 列幅の最大数
+
+def main(items)
+  taken_items = take_items(items)
+  sliced_items = slice_items(taken_items)
+  sorted_items = sort_items(sliced_items)
+  display_items(sorted_items)
+end
+
+def take_items(items)
+  items.concat(Dir.glob('*'))
+end
+
+def slice_items(taken_items)
+  order_id = if (taken_items.size % NUM_COLUMNS).zero?
+               taken_items.size / NUM_COLUMNS.ceil # NUM_COLUMNSの倍数の時だけ、NUM_COLUMNSで割り込む
+             else
+               taken_items.size / NUM_COLUMNS.ceil + 1 # 最大NUM_COLUMNS列に収める
+             end
+  taken_items.each_slice(order_id).to_a
+end
+
+def sort_items(sliced_items)
+  if (0..NUM_COLUMNS).cover?(sliced_items.flatten.size)
+    sliced_items.flatten
+  else
+    max_size = sliced_items.map(&:size).max
+    sliced_items.each do |item| # サブ配列の要素数を揃える
+      item << nil while item.size < max_size
+    end
+  end
+  sliced_items.transpose
+end
+
+def display_items(sorted_items)
+  max_word_count = sorted_items.flatten.compact.map(&:size).max
+  if (0..NUM_COLUMNS).cover?(sorted_items.flatten.size)
+    sorted_items.flatten.map do |item|
+      print item.to_s.ljust(max_word_count + 5)
+    end
+    puts
+  else
+    sorted_items.each do |items|
+      items.compact.each do |item|
+        print item.ljust(max_word_count + 5)
+      end
+      puts
+    end
+  end
+end
+
+main(items)