tidy up

src/day_1.rs

@@ -1,4 +1,4 @@
-pub fn part_1(input: &String) -> String {
+pub fn part_1(input: &String) -> u64 {
     let elves: Vec<&str> = input.split("\n\n").collect();
 
     let mut highest_calorie_count: u64 = 0;
@@ -15,7 +15,7 @@ pub fn part_1(input: &String) -> String {
         }
     }
 
-    format!("{highest_calorie_count}")
+    highest_calorie_count
 }
 
 pub fn part_2(input: &String) -> u64 {