feat: Day 4

aoc_2025/src/day1.rs

@@ -1,4 +1,4 @@
-use crate::AoC;
+use crate::{AoC, WinnowDay};
 use winnow::{
     Parser, Result,
     ascii::{digit1, multispace0},
@@ -11,11 +11,12 @@ enum Side {
     Right(i64),
 }
 
-const AOC: AoC<Parsed> = AoC::new(parse, part1, part2);
+fn day() -> impl WinnowDay {
+    AoC::new(parse as _, part1 as _, part2 as _)
+}
 
-fn parse(input: String) -> Parsed {
-    let mut input: &str = input.as_str();
-    repeat(1.., parse_line).parse_next(&mut input).unwrap()
+fn parse(input: &mut &str) -> Result<Parsed> {
+    repeat(1.., parse_line).parse_next(input)
 }
 
 fn parse_line(input: &mut &str) -> Result<Side> {
@@ -34,7 +35,7 @@ fn parse_right(input: &mut &str) -> Result<Side> {
         .parse_next(input)
 }
 
-fn part1(input: &Parsed) -> String {
+fn part1(input: Parsed) -> String {
     let mut res = 0;
     let mut pos = 50i64;
     for change in input {
@@ -49,12 +50,12 @@ fn part1(input: &Parsed) -> String {
     format!("{res}")
 }
 
-fn part2(input: &Parsed) -> String {
+fn part2(input: Parsed) -> String {
     let input = input
         .iter()
         .flat_map(|side| match side {
-            Side::Left(dx) => (0..*dx).map(|i| Side::Left(1)).collect::<Vec<Side>>(),
-            Side::Right(dx) => (0..*dx).map(|i| Side::Right(1)).collect::<Vec<Side>>(),
+            Side::Left(dx) => (0..*dx).map(|_| Side::Left(1)).collect::<Vec<Side>>(),
+            Side::Right(dx) => (0..*dx).map(|_| Side::Right(1)).collect::<Vec<Side>>(),
         })
         .collect::<Vec<Side>>();
     let mut res = 0;
@@ -73,11 +74,13 @@ fn part2(input: &Parsed) -> String {
 
 #[cfg(test)]
 mod tests {
+    use crate::Day;
+
     use super::*;
 
     #[test]
     fn part1_test() {
-        AOC.assert1(
+        day().assert1(
             "L68
 L30
 R48
@@ -94,12 +97,12 @@ L82",
 
     #[test]
     fn part1_solve() {
-        AOC.assert1(include_str!("../input/day1.txt"), "982");
+        day().assert1(include_str!("../input/day1.txt"), "982");
     }
 
     #[test]
     fn part2_test() {
-        AOC.assert2(
+        day().assert2(
             "L68
 L30
 R48
@@ -116,6 +119,6 @@ L82",
 
     #[test]
     fn part2_solve() {
-        AOC.assert2(include_str!("../input/day1.txt"), "6106");
+        day().assert2(include_str!("../input/day1.txt"), "6106");
     }
 }

aoc_2025/src/day2.rs

@@ -1,4 +1,4 @@
-use crate::AoC;
+use crate::{AoC, WinnowDay};
 use winnow::{
     Parser, Result,
     ascii::digit1,
@@ -7,20 +7,19 @@ use winnow::{
 
 type Parsed = Vec<(u64, u64)>;
 
-const AOC: AoC<Parsed> = AoC::new(parse, part1, part2);
+fn day() -> impl WinnowDay {
+    AoC::new(parse as _, part1 as _, part2 as _)
+}
 
-fn parse(input: String) -> Parsed {
-    let mut input: &str = input.as_str();
-    separated(1.., parse_range, ",")
-        .parse_next(&mut input)
-        .unwrap()
+fn parse(input: &mut &str) -> Result<Parsed> {
+    separated(1.., parse_range, ",").parse_next(input)
 }
 
 fn parse_range(input: &mut &str) -> Result<(u64, u64)> {
     separated_pair(digit1.parse_to(), "-", digit1.parse_to()).parse_next(input)
 }
 
-fn part1(input: &Parsed) -> String {
+fn part1(input: Parsed) -> String {
     let res = input
         .iter()
         .map(|(from, to)| {
@@ -36,13 +35,13 @@ fn part1(input: &Parsed) -> String {
     format!("{res}")
 }
 
-fn part2(input: &Parsed) -> String {
+fn part2(input: Parsed) -> String {
     let res = input
         .iter()
         .map(|(from, to)| {
             (*from..=*to)
                 .filter(|i| {
-                    let n = (i.ilog10() + 1);
+                    let n = i.ilog10() + 1;
                     (1..=(n >> 1)).filter(|p| n % p == 0).any(|p| {
                         (1..(n / p))
                             .all(|s| i % 10u64.pow(p) == (i / 10u64.pow(p * s)) % 10u64.pow(p))
@@ -56,11 +55,13 @@ fn part2(input: &Parsed) -> String {
 
 #[cfg(test)]
 mod tests {
+    use crate::Day;
+
     use super::*;
 
     #[test]
     fn part1_test() {
-        AOC.assert1(
+        day().assert1(
             "11-22,95-115,998-1012,1188511880-1188511890,222220-222224,1698522-1698528,446443-446449,38593856-38593862,565653-565659,824824821-824824827,2121212118-2121212124",
             "1227775554",
         );
@@ -68,12 +69,12 @@ mod tests {
 
     #[test]
     fn part1_solve() {
-        AOC.assert1(include_str!("../input/day2.txt"), "12599655151");
+        day().assert1(include_str!("../input/day2.txt"), "12599655151");
     }
 
     #[test]
     fn part2_test() {
-        AOC.assert2(
+        day().assert2(
             "11-22,95-115,998-1012,1188511880-1188511890,222220-222224,1698522-1698528,446443-446449,38593856-38593862,565653-565659,824824821-824824827,2121212118-2121212124",
             "4174379265",
         );
@@ -81,6 +82,6 @@ mod tests {
 
     #[test]
     fn part2_solve() {
-        AOC.assert2(include_str!("../input/day2.txt"), "20942028255");
+        day().assert2(include_str!("../input/day2.txt"), "20942028255");
     }
 }

aoc_2025/src/day3.rs

@@ -0,0 +1,102 @@
+use std::iter::Sum;
+
+use crate::{AoC, WinnowDay};
+use winnow::{
+    Parser, Result,
+    ascii::newline,
+    combinator::{repeat, terminated},
+    error::ContextError,
+    token::one_of,
+};
+
+fn day() -> impl WinnowDay {
+    AoC::new(parse as _, part1 as _, part2 as _)
+}
+
+fn parse(input: &mut &str) -> Result<Vec<Vec<usize>>> {
+    repeat(1.., parse_line).parse_next(input)
+}
+
+fn parse_line(input: &mut &str) -> Result<Vec<usize>, ContextError> {
+    terminated(
+        repeat(
+            1..,
+            one_of(('0'..='9',)).map(|c: char| c.to_string().parse::<usize>().unwrap()),
+        ),
+        newline,
+    )
+    .parse_next(input)
+}
+
+fn part1(input: Vec<Vec<usize>>) -> usize {
+    input.iter().map(joltage(2)).sum()
+}
+
+fn part2(input: Vec<Vec<usize>>) -> usize {
+    input.iter().map(joltage(12)).sum()
+}
+
+fn joltage<
+    'a,
+    B: IntoIterator<IntoIter = I> + Copy,
+    I: ExactSizeIterator<Item = &'a N>,
+    N: Sum<&'a N> + Into<usize> + From<usize> + Copy + Default + 'a,
+>(
+    size: usize,
+) -> impl Fn(B) -> N {
+    move |line| {
+        (line.into_iter().len() - size..line.into_iter().len())
+            .fold((0, 0), |(start, val), end| {
+                line.into_iter()
+                    .enumerate()
+                    .skip(start)
+                    .take(end - start + 1)
+                    .map(|(i, v)| (i + 1, (*v).into() + val * 10))
+                    .reduce(|a, b| if a.1 >= b.1 { a } else { b })
+                    .unwrap()
+            })
+            .1
+            .into()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::Day;
+
+    use super::*;
+
+    #[test]
+    fn part1_test() {
+        day().assert1(
+            "987654321111111
+811111111111119
+234234234234278
+818181911112111
+",
+            "357",
+        );
+    }
+
+    #[test]
+    fn part1_solve() {
+        day().assert1(include_str!("../input/day3.txt"), "17343");
+    }
+
+    #[test]
+    fn part2_test() {
+        day().assert2(
+            "987654321111111
+811111111111119
+234234234234278
+818181911112111
+",
+            "3121910778619",
+        );
+    }
+
+    #[test]
+    fn part2_solve() {
+        day().assert2(include_str!("../input/day3.txt"), "172664333119298");
+    }
+}

aoc_2025/src/day4.rs

@@ -0,0 +1,155 @@
+use winnow::{
+    Parser, Result,
+    ascii::{multispace0, newline},
+    combinator::{alt, preceded, repeat, terminated},
+};
+
+use crate::{AoC, SimpleDay, WinnowDay};
+
+fn day() -> impl WinnowDay {
+    AoC::new(parse as _, part1 as _, part2 as _)
+}
+
+type Parsed = Vec<Vec<Cell>>;
+
+#[derive(Debug, PartialEq, Eq)]
+enum Cell {
+    Empty,
+    Paper,
+}
+
+impl Cell {
+    fn is_empty(&self) -> bool {
+        self == &Cell::Empty
+    }
+
+    fn is_paper(&self) -> bool {
+        self == &Cell::Paper
+    }
+}
+
+fn parse(input: &mut &str) -> Result<Parsed> {
+    repeat(1.., preceded(multispace0, parse_line)).parse_next(input)
+}
+
+fn parse_line(input: &mut &str) -> Result<Vec<Cell>> {
+    repeat(1.., parse_cell).parse_next(input)
+}
+
+fn parse_cell(input: &mut &str) -> Result<Cell> {
+    alt((".".map(|_| Cell::Empty), "@".map(|_| Cell::Paper))).parse_next(input)
+}
+
+fn part1(input: Parsed) -> usize {
+    let mut input = input;
+    remove_paper(&mut input)
+}
+
+fn remove_paper(input: &mut [Vec<Cell>]) -> usize {
+    let mut score = 0;
+    let mut access = Vec::new();
+    let h = input.len();
+    let w = input[0].len();
+    let directions = [
+        (-1, -1),
+        (0, -1),
+        (1, -1),
+        (1, 0),
+        (1, 1),
+        (0, 1),
+        (-1, 1),
+        (-1, 0),
+    ];
+    for y in 0..h {
+        for x in 0..w {
+            match input[y][x] {
+                Cell::Empty => {}
+                Cell::Paper => {
+                    let count = directions
+                        .iter()
+                        .filter(|dir| {
+                            let nx = x as isize + dir.0;
+                            let ny = y as isize + dir.1;
+                            nx >= 0
+                                && nx < w as isize
+                                && ny >= 0
+                                && ny < h as isize
+                                && input[ny as usize][nx as usize].is_paper()
+                        })
+                        .count();
+                    if count < 4 {
+                        score += 1;
+                        access.push((x, y));
+                    }
+                }
+            }
+        }
+    }
+    access.iter().for_each(|(x, y)| {
+        input[*y][*x] = Cell::Empty;
+    });
+    score
+}
+
+fn part2(input: Parsed) -> usize {
+    let mut input = input;
+    let mut score = 0;
+    loop {
+        let removed = remove_paper(&mut input);
+        score += removed;
+        if removed == 0 {
+            return score;
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::Day;
+
+    use super::*;
+
+    #[test]
+    fn part1_test() {
+        day().assert1(
+            "..@@.@@@@.
+@@@.@.@.@@
+@@@@@.@.@@
+@.@@@@..@.
+@@.@@@@.@@
+.@@@@@@@.@
+.@.@.@.@@@
+@.@@@.@@@@
+.@@@@@@@@.
+@.@.@@@.@.",
+            "13",
+        );
+    }
+
+    #[test]
+    fn part1_solve() {
+        day().assert1(include_str!("../input/day4.txt"), "1356");
+    }
+
+    #[test]
+    fn part2_test() {
+        day().assert2(
+            "..@@.@@@@.
+@@@.@.@.@@
+@@@@@.@.@@
+@.@@@@..@.
+@@.@@@@.@@
+.@@@@@@@.@
+.@.@.@.@@@
+@.@@@.@@@@
+.@@@@@@@@.
+@.@.@@@.@.",
+            "43",
+        );
+    }
+
+    #[test]
+    fn part2_solve() {
+        day().assert2(include_str!("../input/day4.txt"), "8713");
+    }
+}

aoc_2025/src/lib.rs

@@ -1,36 +1,99 @@
 #![allow(dead_code)]
 #![allow(unused)]
 
-mod day2;
+use std::fmt::{Debug, Display};
 
-struct AoC<T> {
-    parse: fn(String) -> T,
-    part1: fn(&T) -> String,
-    part2: fn(&T) -> String,
+use winnow::Parser;
+
+mod day1;
+mod day2;
+mod day3;
+mod day4;
+
+trait Day {
+    fn assert1(&self, input: &str, output: &str);
+    fn assert2(&self, input: &str, output: &str);
 }
 
-impl<T> AoC<T> {
-    const fn new(parse: fn(String) -> T, part1: fn(&T) -> String, part2: fn(&T) -> String) -> Self {
+struct AoC<P, O1, O2> {
+    parse: P,
+    part1: O1,
+    part2: O2,
+}
+
+impl<P, O1, O2> AoC<P, O1, O2> {
+    fn new(parse: P, part1: O1, part2: O2) -> Self {
         Self {
             parse,
             part1,
             part2,
         }
     }
+}
 
+trait SimpleDay: Day {}
+
+impl<P, O1, O2> SimpleDay for AoC<fn(String) -> P, fn(P) -> O1, fn(P) -> O2>
+where
+    O1: Display,
+    O2: Display,
+{
+}
+
+impl<P, O1, O2> Day for AoC<fn(String) -> P, fn(P) -> O1, fn(P) -> O2>
+where
+    O1: Display,
+    O2: Display,
+{
     fn assert1(&self, input: &str, output: &str) {
-        let parsed = (self.parse)(input.into());
-        assert_eq!((self.part1)(&parsed), output);
+        let parsed = (self.parse)(input.to_string());
+        assert_eq!(format!("{}", (self.part1)(parsed)), output);
     }
 
     fn assert2(&self, input: &str, output: &str) {
-        let parsed = (self.parse)(input.into());
-        assert_eq!((self.part2)(&parsed), output);
+        let parsed = (self.parse)(input.to_string());
+        assert_eq!(format!("{}", (self.part2)(parsed)), output);
+    }
 }
 
-    fn apply(&self, input: &str) {
-        let parsed = (self.parse)(input.into());
-        println!("Part 1: {}", (self.part1)(&parsed));
-        println!("Part 2: {}", (self.part2)(&parsed));
+trait WinnowDay: Day {}
+
+impl<O, E, O1, O2> WinnowDay
+    for AoC<for<'a, 'b> fn(&'a mut &'b str) -> Result<O, E>, fn(O) -> O1, fn(O) -> O2>
+where
+    E: Debug,
+    O1: Display,
+    O2: Display,
+{
+}
+
+fn as_parser<O, E>(
+    func: for<'a, 'b> fn(&'a mut &'b str) -> Result<O, E>,
+) -> impl for<'a> Parser<&'a str, O, E>
+where
+    E: Debug,
+{
+    func
+}
+
+impl<O, E, O1, O2> Day
+    for AoC<for<'a, 'b> fn(&'a mut &'b str) -> Result<O, E>, fn(O) -> O1, fn(O) -> O2>
+where
+    E: Debug,
+    O1: Display,
+    O2: Display,
+{
+    fn assert1(&self, input: &str, output: &str) {
+        let mut input = input;
+        let mut parser = as_parser(self.parse);
+        let parsed = parser.parse_next(&mut input).unwrap();
+        assert_eq!(format!("{}", (self.part1)(parsed)), output);
+    }
+
+    fn assert2(&self, input: &str, output: &str) {
+        let mut input = input;
+        let mut parser = as_parser(self.parse);
+        let parsed = parser.parse_next(&mut input).unwrap();
+        assert_eq!(format!("{}", (self.part2)(parsed)), output);
     }
 }

aoc_2025/src/template.rs

@@ -1,46 +1,48 @@
-use crate::AoC;
 use winnow::{Parser, Result};
 
-type Parsed = String;
+use crate::{AoC, SimpleDay, WinnowDay};
 
-const AOC: AoC<Parsed> = AoC::new(parse, part1, part2);
-
-fn parse(input: String) -> Parsed {
-    let mut input: &str = input.as_str();
-    String::new()
+fn day() -> impl WinnowDay {
+    AoC::new(parse as _, part1 as _, part2 as _)
 }
 
-fn part1(input: &Parsed) -> String {
-    let res = 0;
-    format!("{res}")
+type Parsed = ();
+
+fn parse(input: &mut &str) -> Result<Parsed> {
+    "".map(|_| ()).parse_next(input)
 }
 
-fn part2(input: &Parsed) -> String {
-    let res = 0;
-    format!("{res}")
+fn part1(input: Parsed) -> usize {
+    0
+}
+
+fn part2(input: Parsed) -> usize {
+    0
 }
 
 #[cfg(test)]
 mod tests {
+    use crate::Day;
+
     use super::*;
 
     #[test]
     fn part1_test() {
-        AOC.assert1("", "");
+        day().assert1("", "");
     }
 
     #[test]
     fn part1_solve() {
-        AOC.assert1(include_str!("../input/day1.txt"), "");
+        day().assert1(include_str!("../input/day.txt"), "");
     }
 
     // #[test]
     // fn part2_test() {
-    //     AOC.assert2("", "");
+    //     day().assert2("", "");
     // }
 
     // #[test]
     // fn part2_solve() {
-    //     AOC.assert2(include_str!("../input/day1.txt"), "");
+    //     day().assert2(include_str!("../input/day.txt"), "");
     // }
 }