Discussion on: Advent of Code 2019 Solution Megathread - Day 1: The Tyranny of the Rocket Equation

(ns ballpointcarrot.aoc
  (:require [clojure.string :as st]))


(defn fuel-cost
  [value]
  (- (Math/floor (/ value 3)) 2))

(defn adj-fuel-cost
  [value]
  (let [fuel (fuel-cost value)]
    (if (pos? fuel)
      fuel
      0)))

(defn p2019-01
  "Calculate Fuel requirements"
  [input]
  (apply +
         (map #(fuel-cost (Integer/parseInt %)) (st/split-lines input))))

(defn recursive-fuel-cost
  [value]
  (loop [remains value
         total 0]
    (if (= remains 0)
      total
      (let [fuel (adj-fuel-cost remains)]
        (recur fuel (+ total fuel))))))

(defn p2019-01-part2
  "Calculate fuel requirements, including weight of fuel"
  [input]
  (apply +
         (map #(recursive-fuel-cost (Integer/parseInt %)) (st/split-lines input))))