some formatting and some optimizations

day1/src/main.rs

@@ -5,16 +5,13 @@ fn main() -> std::io::Result<()>{
     let file = File::open("input")?;
     let reader = BufReader::new(file);
 
-    let mut elves = reader.lines()
-        .fold(Vec::new(), |mut acc, line| {
+    let mut elves = reader.lines().fold(vec![0_u64], |mut acc, line| {
         let line = line.unwrap();
         //empty lines mean new elf
-            if line.is_empty() || acc.is_empty() {
+        if line.is_empty() {
             acc.push(0_u64);
-            }
-
+        } else {
             // the first time through is an edge case preventing an else here
-            if ! line.is_empty() {
             let last = acc.last_mut().unwrap();
             *last += line.parse::<u64>().unwrap();
         }

day2/src/main.rs

@@ -57,7 +57,7 @@ struct Game{
 impl std::str::FromStr for Game {
     type Err = HoHoError;
     fn from_str(s: &str) -> Result<Self, Self::Err> {
-        let str_split = s.split(" ").collect::<Vec<&str>>();
+        let str_split = s.split(' ').collect::<Vec<&str>>();
         let opponent: Choice = str_split[0].parse()?;
         // game1
         //let you: Choice = str_split[1].parse()?;
@@ -65,7 +65,7 @@ impl std::str::FromStr for Game {
             "X" => opponent.beats(),
             "Y" => str_split[0].parse()?,
             "Z" => opponent.loses(),
-            _ => return Err(HoHoError{})
+            _ => return Err(HoHoError {}),
         };
         Ok(Game { opponent, you })
     }

day3/src/main.rs

@@ -24,7 +24,8 @@ fn main() -> std::io::Result<()> {
     */
     //part 2
     // fold the lines into groups of three
-    let value = reader.lines()
+    let value = reader
+        .lines()
         .fold(Vec::new(), |mut acc: Vec<Vec<String>>, line| {
             if acc.is_empty() || acc.last().unwrap().len() == 3 {
                 acc.push(Vec::new())
@@ -38,7 +39,8 @@ fn main() -> std::io::Result<()> {
                 [g1, g2, g3] => (g1, g2, g3),
                 _ => panic!("not get here"),
             };
-            match g1.chars() 
+            match g1
+                .chars()
                 .fold(Vec::new(), |mut combo: Vec<char>, ch| {
                     if g2.contains(ch) {
                         combo.push(ch)
@@ -46,14 +48,15 @@ fn main() -> std::io::Result<()> {
                     combo
                 })
                 .iter()
-                .find(|c| {
-                    g3.contains(**c)
-                }).unwrap(){
+                .find(|c| g3.contains(**c))
+                .unwrap()
+            {
                 n @ 'a'..='z' => (*n as i32) - ('a' as i32) + 1_i32,
                 n @ 'A'..='Z' => (*n as i32) - ('A' as i32) + 27_i32,
                 _ => 0,
             }
-        }).sum::<i32>();
+        })
+        .sum::<i32>();
     println!("Part 2: {value}");
     // find common letter in the groups
     //   find common letters in the first 2 then find the common in the third