Move code into a single cargo module with an execution harness.

2022/src/day01.rs

@@ -30,13 +30,13 @@ fn update_max(max: &mut SortedVec<i32>, current: i32, step: i32) {
     }
 }
 
-fn main() -> Result<(), io::Error> {
+pub fn execute() -> Result<(), io::Error> {
     let step = get_step();
 
     let mut max: SortedVec<i32> = SortedVec::new();
     let mut current = 0;
 
-    for line in read_lines("input.txt")? {
+    for line in read_lines("input/day01.txt")? {
         let text = line?;
         current = match text.parse::<i32>() {
             Ok(value) => current + value,

2022/src/day02.rs

@@ -11,11 +11,11 @@ fn print_step(step: i8, value: u64) {
     println!("Step {} solution: {}", step, value);
 }
 
-fn main() -> Result<(), io::Error> {
+pub fn execute() -> Result<(), io::Error> {
     let mut score1: u64 = 0;
     let mut score2: u64 = 0;
 
-    for line in read_lines("input.txt")? {
+    for line in read_lines("input/day02.txt")? {
         let text = line?;
         let opp = parse_move(text.chars().nth(0).unwrap());
 

2022/src/main.rs

@@ -0,0 +1,73 @@
+use std::env;
+use std::io;
+
+const LATEST: u8 = 2;
+
+mod day01;
+mod day02;
+// mod day03;
+// mod day04;
+// mod day05;
+// mod day06;
+// mod day07;
+// mod day08;
+// mod day09;
+// mod day10;
+// mod day11;
+// mod day12;
+// mod day13;
+// mod day14;
+// mod day15;
+// mod day16;
+// mod day17;
+// mod day18;
+// mod day19;
+// mod day20;
+// mod day21;
+// mod day22;
+// mod day23;
+// mod day24;
+// mod day25;
+
+fn main() -> io::Result<()> {
+    let day = determine_day(LATEST);
+    match day {
+        1 => day01::execute(),
+        2 => day02::execute(),
+        // 3 => day03::execute(),
+        // 4 => day04::execute(),
+        // 5 => day05::execute(),
+        // 6 => day06::execute(),
+        // 7 => day07::execute(),
+        // 8 => day08::execute(),
+        // 9 => day09::execute(),
+        // 10 => day10::execute(),
+        // 11 => day11::execute(),
+        // 12 => day12::execute(),
+        // 13 => day13::execute(),
+        // 14 => day14::execute(),
+        // 15 => day15::execute(),
+        // 16 => day16::execute(),
+        // 17 => day17::execute(),
+        // 18 => day18::execute(),
+        // 19 => day19::execute(),
+        // 20 => day20::execute(),
+        // 21 => day21::execute(),
+        // 22 => day22::execute(),
+        // 23 => day23::execute(),
+        // 24 => day24::execute(),
+        // 25 => day25::execute(),
+        _ => panic!("Couldn't execute day {day}")
+    }
+}
+
+fn determine_day(latest: u8) -> u8 {
+    let mut day = latest;
+    for arg in env::args() {
+        if let Ok(x) = arg.parse::<u8>() {
+            day = x;
+            break;
+        }
+    }
+    return day;
+}