day four

dayfour.go

@@ -0,0 +1,21 @@
+package main
+
+func incrementIfEncapsulated(pair [2][2]int, solution *int) {
+	if isEncapsulated(pair[0], pair[1]) {
+		*solution++
+	}
+}
+
+func isEncapsulated(first [2]int, second [2]int) bool {
+	return first[0] <= second[0] && first[1] >= second[1] || second[0] <= first[0] && second[1] >= first[1]
+}
+
+func dayFour(input [][2][2]int) int {
+	solution := 0
+
+	for _, pair := range input {
+		incrementIfEncapsulated(pair, &solution)
+	}
+
+	return solution
+}