feat(tazjin/aoc2022): at least do day 1 r/5437

this way I can at least claim to not have completely ignored it this
year :p

Change-Id: I59ab58a05e6bc217e9c6d9fa830d321ddff71d8a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7608
Autosubmit: tazjin <tazjin@tvl.su>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI

1 files changed, 27 insertions, 0 deletions

diff --git a/users/tazjin/aoc2022/day1.rs b/users/tazjin/aoc2022/day1.rs
new file mode 100644
index 000000000000..078eb25f037b
--- /dev/null
+++ b/users/tazjin/aoc2022/day1.rs
@@ -0,0 +1,27 @@
+// AoC 2022 - day 1.
+
+fn sum_elf(elf: &str) -> usize {
+    elf.lines()
+        .map(|s| s.parse::<usize>().expect("invalid input"))
+        .sum()
+}
+
+fn group_by_elf(input: &str) -> Vec<usize> {
+    input.rsplit("\n\n").map(sum_elf).collect()
+}
+
+fn top_elf(input: &str) -> usize {
+    group_by_elf(&input).into_iter().max().unwrap()
+}
+
+fn top_n_elves(n: usize, input: &str) -> usize {
+    let mut by_elf = group_by_elf(input);
+    by_elf.sort_by(|a, b| b.cmp(a)); // high->low
+    (by_elf[..n]).iter().sum()
+}
+
+fn main() {
+    let input = std::fs::read_to_string("input").expect("input should be in file named 'input'");
+    println!("top elf: {}", top_elf(&input));
+    println!("top 3 elves: {}", top_n_elves(3, &input));
+}