Day 1, puzzle 2

Cargo.lock

@@ -3,5 +3,5 @@
 version = 3
 
 [[package]]
-name = "aoc23"
+name = "aoc22"
 version = "0.1.0"

Cargo.toml

@@ -1,5 +1,5 @@
 [package]
-name = "aoc23"
+name = "aoc22"
 version = "0.1.0"
 edition = "2021"
 
@@ -9,4 +9,3 @@ edition = "2021"
 
 [[bin]]
 name = "d1p1"
-path = "src/d1p1.rs"

src/bin/d1p1.rs

@@ -0,0 +1,8 @@
+use aoc22::day1;
+
+fn main() {
+    let elves = day1::read_elves();
+
+    let max = elves.iter().max().unwrap();
+    println!("The elf with the most calories is carrying {} cal", max);
+}

src/bin/d1p2.rs

@@ -0,0 +1,15 @@
+use aoc22::day1;
+use aoc22::util;
+
+const N_ELVES: usize = 3;
+
+fn main() {
+    let elves = day1::read_elves();
+
+    let max_vals = util::max_n(elves.as_slice(), N_ELVES).unwrap();
+    println!(
+        "The {} elves with the most calories are carrying {} cal",
+        N_ELVES,
+        max_vals.iter().sum::<u32>()
+    );
+}

src/day1.rs

@@ -1,6 +1,6 @@
 use std::io;
 
-fn main() {
+pub fn read_elves() -> Vec<u32> {
     println!("What's the calorie list?");
     let lines = io::stdin().lines();
     let mut was_empty = false;
@@ -23,6 +23,5 @@ fn main() {
         elves.push(prev_calories + calories);
     }
 
-    let max = elves.iter().max().unwrap();
-    println!("The elf with the most calories is carrying {} cal", max);
+    elves
 }

src/lib.rs

@@ -0,0 +1,2 @@
+pub mod day1;
+pub mod util;

src/util.rs

@@ -0,0 +1,24 @@
+pub fn max_n<T: Ord + Copy>(slice: &[T], n: usize) -> Result<Vec<T>, ()> {
+    if n == 0 || n > slice.len() {
+        return Err(());
+    }
+    let mut max_vals = Vec::new();
+    for _ in 0..n {
+        max_vals.push(slice[0]);
+    }
+
+    for val in slice {
+        if val > &max_vals[0] {
+            max_vals[2] = max_vals[1];
+            max_vals[1] = max_vals[0];
+            max_vals[0] = *val;
+        } else if val > &max_vals[1] {
+            max_vals[2] = max_vals[1];
+            max_vals[1] = *val;
+        } else if val > &max_vals[2] {
+            max_vals[2] = *val;
+        }
+    }
+
+    Ok(max_vals)
+}