2019: day01: part 1

aoc2019/src/day01.rs

@@ -0,0 +1,42 @@
+use super::Result;
+
+const INPUT: &str = include_str!("../input/day01.txt");
+
+pub fn run() -> Result<()> {
+    println!("part 1: {}", part1(INPUT)?);
+
+    Ok(())
+}
+
+fn fuel_needed(module_weight: u64) -> u64 {
+    (module_weight / 3) - 2
+}
+
+fn part1(input: &str) -> Result<u64> {
+    input
+        .lines()
+        .map(|line| line.parse::<u64>())
+        .map(|w| match w {
+            Ok(w) => Ok(fuel_needed(w)),
+            Err(e) => Err(Box::from(e)),
+        })
+        .sum()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn part1_provided() {
+        assert_eq!(fuel_needed(12), 2);
+        assert_eq!(fuel_needed(14), 2);
+        assert_eq!(fuel_needed(1969), 654);
+        assert_eq!(fuel_needed(100756), 33583);
+    }
+
+    #[test]
+    fn part1_real() {
+        assert_eq!(part1(INPUT).unwrap(), 3268951);
+    }
+}

aoc2019/src/lib.rs

@@ -0,0 +1,8 @@
+pub mod day01;
+
+pub type Result<T> = std::result::Result<T, Box<dyn std::error::Error>>;
+
+#[macro_export]
+macro_rules! err {
+    ($($string:expr),+) => (Box::<dyn Error>::from(format!($($string),+)))
+}

aoc2019/src/main.rs

@@ -0,0 +1,29 @@
+use std::env;
+
+use aoc2019::day01;
+
+use aoc2019::Result;
+
+fn main() -> Result<()> {
+    let days: &[fn() -> Result<()>] = &[day01::run];
+
+    let mut args = env::args();
+    args.next();
+
+    match args.next() {
+        Some(arg) => {
+            let day: usize = arg.parse().expect("Please provide a day number");
+            days[day - 1]().expect("error running day specified");
+        }
+        None => {
+            for (i, day) in days.iter().enumerate() {
+                let i = i + 1;
+                println!("day{}: ", i);
+                day().unwrap_or_else(|e| panic!("error running day {}: {}", i, e));
+                println!();
+            }
+        }
+    }
+
+    Ok(())
+}