Add day01, 2022

1 files changed, 64 insertions, 0 deletions

diff --git a/2022/rust/day01/src/main.rs b/2022/rust/day01/src/main.rs
new file mode 100644
index 0000000..a0c5bae
--- /dev/null
+++ b/2022/rust/day01/src/main.rs
@@ -0,0 +1,64 @@
+use {
+    anyhow::{
+        anyhow,
+        Context,
+        Result,
+    },
+    std::{
+        env::args,
+        fs::File,
+        io::{
+            BufRead,
+            BufReader,
+        },
+        path::Path,
+    },
+};
+
+fn read_input<T: AsRef<Path>>(filename: T) -> Result<Vec<Vec<usize>>> {
+    let reader = BufReader::new(File::open(filename)?);
+
+    let mut elves = vec![vec![]];
+
+    for line in reader.lines() {
+        let s = line?;
+        if s.is_empty() {
+            elves.push(vec![]);
+            continue;
+        }
+        let elf = elves.last_mut().context("Invalid elves vector.")?;
+        let n = s.parse().context("Could not parse {s}")?;
+        elf.push(n);
+    }
+
+    Ok(elves)
+}
+
+fn part1<'a, I: IntoIterator<Item = &'a Vec<usize>>>(input: I) -> Result<usize> {
+    input.into_iter().map(|foodpacks| foodpacks.iter().sum()).max()
+        .context("Iterator chain in first part failed.")
+}
+
+fn part2<'a, I: IntoIterator<Item = &'a Vec<usize>>>(input: I) -> Result<usize> {
+    let mut calories: Vec<usize> = input.into_iter().map(|foodpacks| foodpacks.iter().sum())
+        .collect();
+    calories.sort();
+
+    Ok(calories.into_iter().rev().take(3).sum::<usize>())
+}
+
+fn main() -> Result<()> {
+    let ( do_part_1, do_part_2 ) = aoc::do_parts();
+
+    let filename = args().nth(1).ok_or_else(|| anyhow!("Missing input filename"))?;
+    let input = read_input(filename).context("Could not read input")?;
+    if do_part_1 {
+        let solution = part1(&input).context("No solution for part 1")?;
+        println!("Part1, solution found to be: {}", solution);
+    }
+    if do_part_2 {
+        let solution = part2(&input).context("No solution for part 2")?;
+        println!("Part2, solution found to be: {}", solution);
+    }
+    Ok(())
+}