Skip to content

Instantly share code, notes, and snippets.

@jcoglan

jcoglan/rocket_fuel.rb

Created December 7, 2019 23:52
Show Gist options

  • Select an option

    Learn more about clone URLs
  • Save jcoglan/783d665d74d7d1643cdcabec1ffe2e09 to your computer and use it in GitHub Desktop.

Select an option

Learn more about clone URLs
Save jcoglan/783d665d74d7d1643cdcabec1ffe2e09 to your computer and use it in GitHub Desktop.
Download ZIP

Revisions

  1. jcoglan created this gist Dec 7, 2019.
    18 changes: 18 additions & 0 deletions rocket_fuel.rb
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,18 @@
    input_path = File.expand_path('../input.txt', __FILE__)
    masses = File.read(input_path).lines.map(&:to_i)

    def fuel(mass)
    (mass / 3.0).floor - 2
    end

    p masses.reduce(0) { |s, m| s + fuel(m) }

    def required_fuel(init)
    Enumerator.produce(fuel(init)) { |mass| fuel(mass) }
    end

    fuels = masses.flat_map do |mass|
    required_fuel(mass).take_while { |f| f > 0 }
    end

    p fuels.reduce(0, :+)
    28 changes: 28 additions & 0 deletions rocket_fuel.rs
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,28 @@
    use std::fs;
    use std::iter;

    fn main() {
    let content = fs::read_to_string("input.txt").unwrap();
    let masses: Vec<f64> = content.lines().flat_map(|line| line.parse()).collect();

    let fuel: f64 = masses.iter().map(|mass| fuel(*mass)).sum();
    println!("{}", fuel);

    let fuel: f64 = masses
    .iter()
    .flat_map(|mass| required_fuel(*mass).take_while(|f| *f > 0.0))
    .sum();

    println!("{}", fuel);
    }

    fn required_fuel(mut mass: f64) -> impl Iterator<Item = f64> {
    iter::from_fn(move || {
    mass = fuel(mass);
    Some(mass)
    })
    }

    fn fuel(mass: f64) -> f64 {
    (mass / 3.0).floor() - 2.0
    }