#7 resubmit day1 solution (#8)

Author: kxa14

src/main/scala/advent/solutions/Day1.scala

@@ -1,5 +1,7 @@
 package advent.solutions
 
+import scala.annotation.tailrec
+
 /** Day 1: The Tyranny of the Rocket Equation
   *
   * @see https://adventofcode.com/2019/day/1
@@ -23,15 +25,22 @@ object Day1 {
     */
   def sumOfFuel(masses: List[Int]): Int = {
     // This should use the Day1.fuel function above
-    ???
+    masses.map(fuel).sum
   }
 
   /** Calculates the total required to launch a module, including the fuel required to launch the fuel itself
     *
     * @param mass The mass of the module
     * @return The fuel required to launch the module, plus the fuel required to launch that fuel
     */
-  def totalFuel(mass: Int): Int = ???
+  def totalFuel(mass: Int): Int = {
+    @tailrec
+    def go(currentFuel: Int, accum: Int): Int =
+      if (currentFuel < 0) accum else go(fuel(currentFuel), accum + currentFuel)
+
+    go(fuel(mass), 0)
+
+  }
 
   /** Calculates the sum of the total fuel required to launch each module of a given mass
     *
@@ -40,7 +49,7 @@ object Day1 {
     */
   def sumOfTotalFuel(masses: List[Int]): Int = {
     // This should use the Day1.totalFuel function above
-    ???
+    masses.map(totalFuel).sum
   }
 
 }