Read input from file

.gitignore

@@ -1 +1,2 @@
 /target
+/input

src/bin/d1p1.rs

@@ -1,7 +1,8 @@
 use aoc22::day1;
+use aoc22::util;
 
 fn main() {
-    let elves = day1::read_elves();
+    let elves = day1::parse_elves(&util::parse_input());
 
     let max = elves.iter().max().unwrap();
     println!("The elf with the most calories is carrying {} cal", max);

src/bin/d1p2.rs

@@ -4,7 +4,7 @@ use aoc22::util;
 const N_ELVES: usize = 3;
 
 fn main() {
-    let elves = day1::read_elves();
+    let elves = day1::parse_elves(&util::parse_input());
 
     let max_vals = util::max_n(elves.as_slice(), N_ELVES).unwrap();
     println!(

src/day1.rs

@@ -1,24 +1,13 @@
-use std::io;
-
-pub fn read_elves() -> Vec<u32> {
-    println!("What's the calorie list?");
-    let lines = io::stdin().lines();
-    let mut was_empty = false;
+pub fn parse_elves(input: &String) -> Vec<u32> {
+    let lines = input.lines();
     let mut elves = vec![0];
     for line in lines {
-        let line_s = line.unwrap();
-        if line_s.is_empty() {
-            if was_empty {
-                break;
-            }
+        if line.is_empty() {
             elves.push(0);
-            was_empty = true;
             continue;
-        } else {
-            was_empty = false;
         }
 
-        let calories: u32 = line_s.parse().expect("Wanted a number");
+        let calories: u32 = line.parse().expect("Wanted a number");
         let prev_calories = elves.pop().unwrap();
         elves.push(prev_calories + calories);
     }

src/util.rs

@@ -1,3 +1,16 @@
+use std::env;
+use std::fs;
+
+pub fn parse_input() -> String {
+    let args: Vec<String> = env::args().collect();
+    let input_path = args
+        .get(1)
+        .expect(format!("Usage: {} INPUT-FILE", args.get(0).unwrap()).as_str());
+
+    fs::read_to_string(input_path)
+        .expect(format!("Couldn't read input file {}", input_path).as_str())
+}
+
 pub fn max_n<T: Ord + Copy>(slice: &[T], n: usize) -> Result<Vec<T>, ()> {
     if n == 0 || n > slice.len() {
         return Err(());