diff --git a/src/day1.rs b/src/day1.rs
index fc20e33..ac9afbf 100644
--- a/src/day1.rs
+++ b/src/day1.rs
@@ -1,9 +1,5 @@
-use std::io::{self, BufRead};
-
-fn increases(measurements: &[u64]) -> u64 {
-    measurements
-        .windows(2)
-        .fold(0, |acc, x| if x[1] > x[0] { acc + 1 } else { acc })
+fn increases(measurements: &[u64]) -> usize {
+    measurements.windows(2).filter(|x| x[1] > x[0]).count()
 }
 
 fn convolve(measurements: &[u64]) -> Vec<u64> {
@@ -12,23 +8,22 @@ fn convolve(measurements: &[u64]) -> Vec<u64> {
 
 fn main() {
     const INPUT: &str = include_str!("../inputs/day1.txt");
-    let measurements: Vec<u64> = io::Cursor::new(INPUT)
+    let measurements = INPUT
         .lines()
-        .map(|line| line.unwrap().parse().unwrap())
-        .collect();
-
+        .map(|line| line.parse().unwrap())
+        .collect::<Vec<u64>>();
     println!("increased {} times", increases(&measurements));
     println!("increased {} times", increases(&convolve(&measurements)));
 }
 
 #[test]
 fn part1_example() {
-    let measurements = vec![199, 200, 208, 210, 200, 207, 240, 269, 260, 263];
+    let measurements = [199, 200, 208, 210, 200, 207, 240, 269, 260, 263];
     assert_eq!(increases(&measurements), 7);
 }
 
 #[test]
 fn part2_example() {
-    let measurements = vec![199, 200, 208, 210, 200, 207, 240, 269, 260, 263];
+    let measurements = [199, 200, 208, 210, 200, 207, 240, 269, 260, 263];
     assert_eq!(increases(&convolve(&measurements)), 5);
 }
diff --git a/src/day12.rs b/src/day12.rs
index 254f011..32f386e 100644
--- a/src/day12.rs
+++ b/src/day12.rs
@@ -33,7 +33,7 @@ fn is_small_cave(cave: &str) -> bool {
     if cave == "start" {
         false
     } else {
-        cave.chars().all(|c| matches!(c, 'a'..='z'))
+        cave.chars().all(|c| c.is_ascii_lowercase())
     }
 }
 
diff --git a/src/day2.rs b/src/day2.rs
index 5108e13..51ab8fb 100644
--- a/src/day2.rs
+++ b/src/day2.rs
@@ -1,5 +1,3 @@
-use std::io::{self, BufRead};
-use std::num::ParseIntError;
 use std::str::FromStr;
 
 enum Action {
@@ -14,30 +12,27 @@ struct Command {
 }
 
 impl FromStr for Command {
-    type Err = ParseIntError;
+    type Err = ();
 
     fn from_str(s: &str) -> Result<Command, Self::Err> {
         let words = s.split_once(' ').unwrap();
         let action = match words.0 {
-            "forward" => Ok(Action::Forward),
-            "down" => Ok(Action::Down),
-            "up" => Ok(Action::Up),
-            _ => Err(()),
+            "forward" => Action::Forward,
+            "down" => Action::Down,
+            "up" => Action::Up,
+            _ => return Err(()),
         };
-        let units = words.1.parse()?;
-        Ok(Command {
-            action: action.unwrap(),
-            units,
-        })
+        let units = words.1.parse().unwrap();
+        Ok(Command { action, units })
     }
 }
 
 fn main() {
     const INPUT: &str = include_str!("../inputs/day2.txt");
-    let commands: Vec<Command> = io::Cursor::new(INPUT)
+    let commands = INPUT
         .lines()
-        .map(|l| l.unwrap().parse().unwrap())
-        .collect();
+        .map(|line| line.parse().unwrap())
+        .collect::<Vec<Command>>();
 
     let mut position = 0;
     let mut depth = 0;
diff --git a/src/day3.rs b/src/day3.rs
index a3281a1..71c1cf9 100644
--- a/src/day3.rs
+++ b/src/day3.rs
@@ -1,5 +1,3 @@
-use std::io::{self, BufRead};
-
 struct Diagnostics<const N: usize> {
     report: Vec<String>,
 }
@@ -88,7 +86,7 @@ impl<const N: usize> Diagnostics<N> {
 
 fn main() {
     const INPUT: &str = include_str!("../inputs/day3.txt");
-    let report: Vec<String> = io::Cursor::new(INPUT).lines().map(|l| l.unwrap()).collect();
+    let report = INPUT.lines().map(|line| line.to_string()).collect::<Vec<String>>();
     let diagnostics = Diagnostics::<12> { report };
 
     println!(