Add day 4 solutions

day4.cr

@@ -0,0 +1,38 @@
+require "advent"
+
+struct Range(B, E)
+  def contains?(other)
+    other.begin >= self.begin && other.end <= self.end
+  end
+
+  def overlaps?(other)
+    these = self.to_a
+    others = other.to_a
+    these.any? { |i| others.includes? i }
+  end
+end
+
+INPUT = input(2022, 4).lines.map do |line|
+  first, second = line.split(",").map do |str|
+    left, right = str.split("-").map &.to_i64
+    left..right
+  end
+  {first, second}
+end
+
+def part1(input)
+  input.count do |pair|
+    l, r = pair
+    l.contains?(r) || r.contains?(l)
+  end
+end
+
+def part2(input)
+  input.count do |pair|
+    l, r = pair
+    l.overlaps?(r)
+  end
+end
+
+puts part1(INPUT.clone)
+puts part2(INPUT.clone)