1 files changed, 20 insertions, 0 deletions
diff --git a/lib/interval.rb b/lib/interval.rb
new file mode 100644
index 0000000..0aa787f
--- /dev/null
+++ b/lib/interval.rb
@@ -0,0 +1,20 @@
+class Interval
+  def initialize(min = Float::INFINITY, max = -Float::INFINITY)
+    @min = min
+    @max = max
+  end
+
+  attr_reader :min, :max
+
+  def size
+    @max - @min
+  end
+
+  def include?(x)
+    min <= x && x <= max
+  end
+
+  def surround?(x)
+    min < x && x < max
+  end
+end