From 15f578525d40a2869e8fc0368cfe918808574cae Mon Sep 17 00:00:00 2001
From: Danila Fedorin <danila.fedorin@gmail.com>
Date: Sat, 5 Dec 2020 21:48:15 -0800
Subject: [PATCH] Add some utility methods for lists of sets.

---
 src/advent/util.cr | 13 +++++++++++++
 1 file changed, 13 insertions(+)
 create mode 100644 src/advent/util.cr

diff --git a/src/advent/util.cr b/src/advent/util.cr
new file mode 100644
index 0000000..3953353
--- /dev/null
+++ b/src/advent/util.cr
@@ -0,0 +1,13 @@
+class Array(T)
+  def union
+    reduce(T.new) do |l, r|
+      l | r
+    end
+  end
+
+  def intersect
+    reduce do |l, r|
+      l & r
+    end
+  end
+end