2019: Day 1 Part 2

2019/day1/part2.rb

@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+def fuel_needed(mass)
+  [(mass / 3).truncate - 2, 0].max
+end
+
+def total_fuel(mass)
+  fuel = 0
+  current = mass
+  while current.positive?
+    current = fuel_needed(current)
+    fuel += current
+  end
+  fuel
+end
+
+fuel = 0
+File.open(File.join(__dir__, 'input')) do |file|
+  file.readlines.each do |line|
+    mass = line.to_i
+    fuel += total_fuel(mass)
+  end
+end
+puts fuel