diff --git a/d01t1/demo_input.txt b/d01t1/demo_input.txt
new file mode 100644
index 0000000..7bbc69a
--- /dev/null
+++ b/d01t1/demo_input.txt
@@ -0,0 +1,4 @@
+1abc2
+pqr3stu8vwx
+a1b2c3d4e5f
+treb7uchet
diff --git a/d01t1/src/main.rs b/d01t1/src/main.rs
index 215022b..5b780da 100644
--- a/d01t1/src/main.rs
+++ b/d01t1/src/main.rs
@@ -1,6 +1,12 @@
+use std::fs::read_to_string;
+
 fn main() {
-    let input = include_str!("../input.txt");
-    let result = input
+    let input = read_to_string("input.txt").unwrap();
+    println!("d01t1: {}", d01t1(&input));
+}
+
+fn d01t1(input: &str) -> u32 {
+    input
         .lines()
         .map(|line| {
             let digits = line
@@ -11,6 +17,15 @@ fn main() {
             num_str.push(*digits.last().unwrap());
             num_str.parse::<u32>().unwrap()
         })
-        .sum::<u32>();
-    println!("d01t1: {result}");
+        .sum::<u32>()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_d01t1() {
+        let input = include_str!("../demo_input.txt");
+        assert_eq!(d01t1(input), 142);
+    }
 }
diff --git a/d01t2/demo_input.txt b/d01t2/demo_input.txt
new file mode 100644
index 0000000..41aa89c
--- /dev/null
+++ b/d01t2/demo_input.txt
@@ -0,0 +1,7 @@
+two1nine
+eightwothree
+abcone2threexyz
+xtwone3four
+4nineeightseven2
+zoneight234
+7pqrstsixteen
diff --git a/d01t2/src/main.rs b/d01t2/src/main.rs
index a3537cf..97d30e7 100644
--- a/d01t2/src/main.rs
+++ b/d01t2/src/main.rs
@@ -1,5 +1,11 @@
+use std::fs::read_to_string;
+
 fn main() {
-    let input = include_str!("../input.txt");
+    let input = read_to_string("input.txt").unwrap();
+    println!("d01t2: {}", d01t2(&input));
+}
+
+fn d01t2(input: &str) -> u32 {
     let translated = input
         .replace("one", "o1e")
         .replace("two", "t2o")
@@ -10,7 +16,7 @@ fn main() {
         .replace("seven", "s7n")
         .replace("eight", "e8t")
         .replace("nine", "n9e");
-    let result = translated
+    translated
         .lines()
         .map(|line| {
             let digits = line
@@ -21,6 +27,15 @@ fn main() {
             num_str.push(*digits.last().unwrap());
             num_str.parse::<u32>().unwrap()
         })
-        .sum::<u32>();
-    println!("d01t2: {result}");
+        .sum::<u32>()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_d01t2() {
+        let input = include_str!("../demo_input.txt");
+        assert_eq!(d01t2(input), 281);
+    }
 }
diff --git a/d02t1/demo_input.txt b/d02t1/demo_input.txt
new file mode 100644
index 0000000..295c36d
--- /dev/null
+++ b/d02t1/demo_input.txt
@@ -0,0 +1,5 @@
+Game 1: 3 blue, 4 red; 1 red, 2 green, 6 blue; 2 green
+Game 2: 1 blue, 2 green; 3 green, 4 blue, 1 red; 1 green, 1 blue
+Game 3: 8 green, 6 blue, 20 red; 5 blue, 4 red, 13 green; 5 green, 1 red
+Game 4: 1 green, 3 red, 6 blue; 3 green, 6 red; 3 green, 15 blue, 14 red
+Game 5: 6 red, 1 blue, 3 green; 2 blue, 1 red, 2 green
diff --git a/d02t1/src/main.rs b/d02t1/src/main.rs
index 035eb5e..70fd7b0 100644
--- a/d02t1/src/main.rs
+++ b/d02t1/src/main.rs
@@ -1,5 +1,11 @@
+use std::fs::read_to_string;
+
 fn main() {
-    let input = include_str!("../input.txt");
+    let input = read_to_string("input.txt").unwrap();
+    println!("d02t1: {}", d02t1(&input));
+}
+
+fn d02t1(input: &str) -> i32 {
     let mut result = 0;
     for line in input.lines() {
         let (game_id, game_values) = line.split_once(": ").unwrap();
@@ -18,5 +24,15 @@ fn main() {
             result += game_id.split_once(' ').unwrap().1.parse::<i32>().unwrap();
         }
     }
-    println!("d02t1: {result}");
+    result
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_d02t1() {
+        let input = include_str!("../demo_input.txt");
+        assert_eq!(d02t1(input), 8);
+    }
 }
diff --git a/d02t2/demo_input.txt b/d02t2/demo_input.txt
new file mode 100644
index 0000000..295c36d
--- /dev/null
+++ b/d02t2/demo_input.txt
@@ -0,0 +1,5 @@
+Game 1: 3 blue, 4 red; 1 red, 2 green, 6 blue; 2 green
+Game 2: 1 blue, 2 green; 3 green, 4 blue, 1 red; 1 green, 1 blue
+Game 3: 8 green, 6 blue, 20 red; 5 blue, 4 red, 13 green; 5 green, 1 red
+Game 4: 1 green, 3 red, 6 blue; 3 green, 6 red; 3 green, 15 blue, 14 red
+Game 5: 6 red, 1 blue, 3 green; 2 blue, 1 red, 2 green
diff --git a/d02t2/src/main.rs b/d02t2/src/main.rs
index 496d941..dd81f5a 100644
--- a/d02t2/src/main.rs
+++ b/d02t2/src/main.rs
@@ -1,6 +1,12 @@
+use std::fs::read_to_string;
+
 fn main() {
-    let input = include_str!("../input.txt");
-    let result = input
+    let input = read_to_string("input.txt").unwrap();
+    println!("d02t2: {}", d02t2(&input));
+}
+
+fn d02t2(input: &str) -> usize {
+    input
         .lines()
         .map(|line| {
             let (_game_id, game_values) = line.split_once(": ").unwrap();
@@ -19,6 +25,15 @@ fn main() {
             });
             min_red * min_green * min_blue
         })
-        .sum::<usize>();
-    println!("d02t2: {result}");
+        .sum::<usize>()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_d02t2() {
+        let input = include_str!("../demo_input.txt");
+        assert_eq!(d02t2(input), 2286);
+    }
 }
diff --git a/d03t1/src/main.rs b/d03t1/src/main.rs
index d111147..510c688 100644
--- a/d03t1/src/main.rs
+++ b/d03t1/src/main.rs
@@ -1,4 +1,7 @@
-use std::collections::{HashSet, VecDeque};
+use std::{
+    collections::{HashSet, VecDeque},
+    fs::read_to_string,
+};
 
 fn dec_if_pos(input: usize) -> usize {
     if input > 0 {
@@ -17,7 +20,11 @@ fn inc_if_lt(input: usize, max: usize) -> usize {
 }
 
 fn main() {
-    let input = include_str!("../input.txt");
+    let input = read_to_string("input.txt").unwrap();
+    println!("d03t1: {}", d03t1(&input));
+}
+
+fn d03t1(input: &str) -> usize {
     let mut result = 0;
     let lines = input.lines().collect::<Vec<_>>();
     let total_lines = lines.len();
@@ -78,5 +85,5 @@ fn main() {
             }
         }
     }
-    println!("d03t1: {result}");
+    result
 }
diff --git a/d03t2/src/main.rs b/d03t2/src/main.rs
index 27499ac..8631c89 100644
--- a/d03t2/src/main.rs
+++ b/d03t2/src/main.rs
@@ -1,4 +1,7 @@
-use std::collections::{HashSet, VecDeque};
+use std::{
+    collections::{HashSet, VecDeque},
+    fs::read_to_string,
+};
 
 fn dec_if_pos(input: usize) -> usize {
     if input > 0 {
@@ -17,7 +20,11 @@ fn inc_if_lt(input: usize, max: usize) -> usize {
 }
 
 fn main() {
-    let input = include_str!("../input.txt");
+    let input = read_to_string("input.txt").unwrap();
+    println!("d03t2: {}", d03t2(&input));
+}
+
+fn d03t2(input: &str) -> usize {
     let mut result = 0;
     let lines = input.lines().collect::<Vec<_>>();
     let total_lines = lines.len();
@@ -80,5 +87,5 @@ fn main() {
             }
         }
     }
-    println!("d03t2: {result}");
+    result
 }
diff --git a/d04t1/src/main.rs b/d04t1/src/main.rs
index fad30ed..b5a666b 100644
--- a/d04t1/src/main.rs
+++ b/d04t1/src/main.rs
@@ -1,6 +1,8 @@
+use std::fs::read_to_string;
+
 fn main() {
-    let input = include_str!("../input.txt");
-    println!("d04t1: {}", d04t1(input));
+    let input = read_to_string("input.txt").unwrap();
+    println!("d04t1: {}", d04t1(&input));
 }
 
 #[must_use]
diff --git a/d04t2/src/main.rs b/d04t2/src/main.rs
index 73f1b92..0df8326 100644
--- a/d04t2/src/main.rs
+++ b/d04t2/src/main.rs
@@ -1,79 +1,65 @@
+use std::fs::read_to_string;
+
 fn main() {
-    let input = include_str!("../input.txt");
-    println!("d04t2: {}", d04t2(input));
+    let input = read_to_string("input.txt").unwrap();
+    println!("d04t2: {}", d04t2(&input));
 }
 
 struct Card {
     card_id: usize,
-    winning_amount: usize,
+    result: usize,
 }
 
 #[must_use]
 pub fn d04t2(input: &str) -> usize {
-    let mut result = 0;
-    let cards: Vec<Card> = input
-        .lines()
-        .map(|line| {
-            let (card_id, card_data) = line
-                .split_once(": ")
-                .map(|(cid, cd)| {
-                    (
-                        cid.split_once(' ')
-                            .unwrap()
-                            .1
-                            .trim()
-                            .parse::<usize>()
-                            .unwrap(),
-                        cd,
-                    )
-                })
-                .unwrap();
-            let (winning_numbers, actual_numbers) = card_data
-                .split_once(" | ")
-                .map(|(a, b)| {
-                    (
-                        a.split_whitespace()
-                            .map(|e| e.parse::<usize>().unwrap())
-                            .collect::<Vec<_>>(),
-                        b.split_whitespace()
-                            .map(|e| e.parse::<usize>().unwrap())
-                            .collect::<Vec<_>>(),
-                    )
-                })
-                .unwrap();
-            let winning_amount = actual_numbers
+    let mut cards: Vec<Card> = Vec::new();
+    for line in input.lines().rev() {
+        let (card_id, card_data) = line
+            .split_once(": ")
+            .map(|(cid, cd)| {
+                (
+                    cid.split_once(' ')
+                        .unwrap()
+                        .1
+                        .trim()
+                        .parse::<usize>()
+                        .unwrap(),
+                    cd,
+                )
+            })
+            .unwrap();
+        let (winning_numbers, actual_numbers) = card_data
+            .split_once(" | ")
+            .map(|(a, b)| {
+                (
+                    a.split_whitespace()
+                        .map(|e| e.parse::<usize>().unwrap())
+                        .collect::<Vec<_>>(),
+                    b.split_whitespace()
+                        .map(|e| e.parse::<usize>().unwrap())
+                        .collect::<Vec<_>>(),
+                )
+            })
+            .unwrap();
+        let winning_amount = actual_numbers
+            .iter()
+            .filter(|num| winning_numbers.contains(num))
+            .count();
+        let mut result = 1;
+        for winning_card in (card_id + 1)..=(card_id + winning_amount) {
+            result += cards
                 .iter()
-                .filter(|num| winning_numbers.contains(num))
-                .count();
-            Card {
-                card_id,
-                winning_amount,
-            }
-        })
-        .collect();
-    for card in &cards {
-        result += 1;
-        println!(
-            "Checking card {} - {} winning",
-            card.card_id, card.winning_amount
-        );
-        result += add_rec(card, &cards);
-    }
-    result
-}
-
-fn add_rec(card: &Card, cards: &Vec<Card>) -> usize {
-    let mut to_add = 0;
-    for cid in 1..=card.winning_amount {
-        let found_card = cards.iter().find(|c| c.card_id == card.card_id + cid);
-        if let Some(found_card) = found_card {
-            to_add += 1;
-            to_add += add_rec(found_card, cards);
-        } else {
-            println!("\tdidn't find card {}", card.card_id + cid);
+                .find(|c| c.card_id == winning_card)
+                .map_or(0, |c| c.result);
         }
+        cards.push(Card { card_id, result });
     }
-    to_add
+    let mut result: usize = 0;
+    for card in &cards {
+        result += card.result;
+    }
+
+    result
 }
 
 #[cfg(test)]
diff --git a/d05t1/src/main.rs b/d05t1/src/main.rs
index 031e359..e8b8b00 100644
--- a/d05t1/src/main.rs
+++ b/d05t1/src/main.rs
@@ -1,6 +1,8 @@
+use std::fs::read_to_string;
+
 fn main() {
-    let input = include_str!("../input.txt");
-    println!("d05t1: {}", d05t1(input));
+    let input = read_to_string("input.txt").unwrap();
+    println!("d05t1: {}", d05t1(&input));
 }
 
 pub fn d05t1(input: &str) -> usize {
diff --git a/d05t2/src/main.rs b/d05t2/src/main.rs
index bad624e..796ac4d 100644
--- a/d05t2/src/main.rs
+++ b/d05t2/src/main.rs
@@ -1,6 +1,8 @@
+use std::fs::read_to_string;
+
 fn main() {
-    let input = include_str!("../input.txt");
-    println!("d05t2: {}", d05t2(input));
+    let input = read_to_string("input.txt").unwrap();
+    println!("d05t2: {}", d05t2(&input));
 }
 
 pub fn d05t2(input: &str) -> usize {