refactored day3 to reduce unneeded mem allocations.

ran rustfmt on all files.

src/day02/part1.rs

@@ -24,7 +24,6 @@ pub fn parse(input: &str) -> Vec<Strategy> {
         .collect()
 }
 
-
 #[cfg(test)]
 mod tests {
     use super::*;

src/day02/utilities.rs

@@ -11,15 +11,14 @@ pub struct Strategy {
     pub you: Play,
 }
 
-pub fn calc_score(input: &Strategy) -> usize{
+pub fn calc_score(input: &Strategy) -> usize {
     //an enum wins if (you-elf)%3 = 1, looses if it = 2
     (match (input.you as i8 - input.elf as i8).rem_euclid(3) {
         1 => 6,
         2 => 0,
         0 => 3,
-        _ => unreachable!("you were {}, elf was {}", input.you as i8, input.elf as i8)
-    //play enum has value corresponding to its score.
-    })+input.you as usize
+        _ => unreachable!("you were {}, elf was {}", input.you as i8, input.elf as i8),
+    }) + input.you as usize //play enum has value corresponding to its score.
 }
 
 #[cfg(test)]
@@ -28,10 +27,10 @@ mod tests {
 
     #[test]
     fn test_calc_score() {
-            let input = Strategy {
-                    elf: Play::Scissors,
-                    you: Play::Scissors
-                };
+        let input = Strategy {
+            elf: Play::Scissors,
+            you: Play::Scissors,
+        };
         assert_eq!(calc_score(&input), 6);
     }
 }

src/day03/part1.rs

@@ -3,19 +3,15 @@ use crate::utilities::*;
 pub fn part1(input: &[Rucksack]) -> usize {
     input
         .iter()
-        .map(|rucksack| {
-            let intersection: Vec<&char> = rucksack.0.intersection(&rucksack.1).collect();
-            assert!(intersection.len() == 1);
-            intersection[0]
-        })
+        .map(|rucksack| rucksack.0.intersection(&rucksack.1).next().unwrap())
         .map(find_char_score)
         .sum()
 }
 
 #[cfg(test)]
 mod tests {
-    use std::collections::HashSet;
     use super::*;
+    use std::collections::HashSet;
 
     #[test]
     fn test_part1() {

src/day03/part2.rs

@@ -13,31 +13,20 @@ pub fn part2(input: &[Rucksack]) -> usize {
                 .iter()
                 .filter(|c| group.1.contains(c))
                 .filter(|c| group.2.contains(c))
-                .map(|x| x.to_owned())
                 .next()
                 .unwrap()
-        }).map(|c| find_char_score(&c)).sum()
+        })
+        .map(find_char_score)
+        .sum()
 }
 
 fn seperate_groups(input: &[Rucksack]) -> Vec<Group> {
     let mut output: Vec<Group> = Vec::new();
     for group in input.chunks_exact(3) {
         output.push(Group(
-            group[0]
-                .0
-                .union(&group[0].1)
-                .map(|x| x.to_owned())
-                .collect(),
-            group[1]
-                .0
-                .union(&group[1].1)
-                .map(|x| x.to_owned())
-                .collect(),
-            group[2]
-                .0
-                .union(&group[2].1)
-                .map(|x| x.to_owned())
-                .collect(),
+            group[0].0.union(&group[0].1).copied().collect(),
+            group[1].0.union(&group[1].1).copied().collect(),
+            group[2].0.union(&group[2].1).copied().collect(),
         ));
     }
     output