Day 1, Part 1! Gold star!

2022/aoc2022/src/day1.rs

@@ -0,0 +1,39 @@
+use std::fs::File;
+use std::io::BufRead;
+use std::io::BufReader;
+use std::io::Lines;
+use std::io::Read;
+use std::io::Result;
+
+fn get_calorie_totals<R: Read + BufRead>(lines: Lines<R>) -> Vec<u32> {
+    let mut elves: Vec<u32> = Vec::new();
+    let mut current_calorie_count: u32 = 0;
+
+    for line in lines {
+        let unwrapped_line = line.unwrap();
+        if unwrapped_line.is_empty() {
+            elves.push(current_calorie_count);
+            println!("Elf {}: {} calories", elves.len(), current_calorie_count);
+            current_calorie_count = 0;
+            continue;
+        }
+
+        let u32_value = u32::from_str_radix(&unwrapped_line, 10)
+            .expect(format!("Couldn't read u32 value from string: {}", unwrapped_line).as_str());
+        current_calorie_count += u32_value;
+    }
+
+    elves.sort_unstable_by(|a, b| b.cmp(a));
+    elves
+}
+
+pub fn main(input_filename: &String) -> Result<()> {
+    let file = File::open(input_filename)?; 
+    let reader = BufReader::new(file);
+
+    let elves = get_calorie_totals(reader.lines());
+
+    println!("Elf with highest calorie count in knapsack: {}", elves[0]);
+
+    Ok(())
+}

2022/aoc2022/src/main.rs

@@ -1,7 +1,12 @@
 use std::env;
 
+mod day1;
+
 fn main() {
     let args: Vec<String> = env::args().collect();
-    dbg!("Command line args: {}", args);
-    println!("Hello, world!");
+    dbg!("Command line args: {}", &args);
+
+    let day1_datafile = &args[1];
+    day1::main(day1_datafile)
+        .expect("Unable to process day1 data file");
 }