4 files changed, 225 insertions, 1 deletions

diff --git a/.idea/aoc2024.iml b/.idea/aoc2024.iml
index 779b5d8..5a17898 100644
--- a/.idea/aoc2024.iml
+++ b/.idea/aoc2024.iml
@@ -7,6 +7,7 @@
       <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
       <sourceFolder url="file://$MODULE_DIR$/day2/src" isTestSource="false" />
       <sourceFolder url="file://$MODULE_DIR$/day3/src" isTestSource="false" />
+      <sourceFolder url="file://$MODULE_DIR$/day4/src" isTestSource="false" />
       <excludeFolder url="file://$MODULE_DIR$/aoc/target" />
       <excludeFolder url="file://$MODULE_DIR$/target" />
     </content>
diff --git a/Cargo.toml b/Cargo.toml
index 2e030b6..fac2cfd 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,3 +1,3 @@
 [workspace]
-members = ["aoc", "day1", "day2", "day3"]
+members = ["aoc", "day1", "day2", "day3", "day4"]
 resolver = "2"
diff --git a/day4/Cargo.toml b/day4/Cargo.toml
new file mode 100644
index 0000000..3161844
--- /dev/null
+++ b/day4/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "day4"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+aoc = { path = "../aoc" }
+regex = "1.11.1"
diff --git a/day4/src/main.rs b/day4/src/main.rs
new file mode 100644
index 0000000..c788292
--- /dev/null
+++ b/day4/src/main.rs
@@ -0,0 +1,215 @@
+use aoc;
+use std::io::{BufRead, BufReader, Read};
+use aoc::Day;
+use regex::Regex;
+
+struct Day4 {}
+
+enum Direction {
+    Horizontal,
+    Vertical,
+    DiagonalDown,
+    DiagonalUp,
+}
+
+impl Day4 {
+    fn parse_input(&self, input: BufReader<Box<dyn Read>>) -> Vec<String> {
+        input
+            .lines()
+            .map(|l| {
+                l
+                    .unwrap()
+                    .trim()
+                    .to_string()
+            })
+            .collect::<Vec<String>>()
+    }
+
+    fn _diagonal_half_loop(&self, input: &Vec<String>) -> Vec<String> {
+        let mut out: Vec<String> = vec![];
+        for y in 0..input.len() {
+            let mut out_row = String::new();
+
+            for (x, row) in input[0..y + 1].iter().rev().enumerate() {
+                out_row.push(row.chars().nth(x).unwrap());
+            }
+
+            out.push(out_row)
+        }
+
+        out
+    }
+
+    fn _rotate(&self, input: &Vec<String>) -> Vec<String> {
+        let mut output: Vec<String> = vec![];
+
+        for (i, _) in input[0].char_indices() {
+            let mut line_out = String::new();
+            for line in input {
+                let a = line.chars().nth(i).unwrap();
+                line_out.push(a)
+            }
+
+            output.push(line_out.chars().rev().collect::<String>());
+        }
+
+        output
+    }
+
+    fn _mirror(&self, input: &Vec<String>) -> Vec<String> {
+        input
+            .iter()
+            .map(|l| {
+                l
+                    .chars()
+                    .rev()
+                    .collect::<String>()
+            })
+            .collect::<Vec<String>>()
+    }
+
+    fn diagonal_loop(&self, input: &Vec<String>) -> Vec<String> {
+        let mut first_half: Vec<String> = self._diagonal_half_loop(input);
+
+        let rev_input = input
+            .iter()
+            .rev()
+            .map(|row| {
+                row
+                    .chars()
+                    .rev()
+                    .collect::<String>()
+            })
+            .collect::<Vec<String>>();
+
+
+        let mut second_half = self
+            ._diagonal_half_loop(&rev_input)
+            .iter()
+            .rev()
+            .collect::<Vec<_>>()[1..]
+            .iter()
+            .map(|row| {
+                row
+                    .chars()
+                    .rev()
+                    .collect::<String>()
+            })
+            .collect::<Vec<String>>();
+
+
+        first_half.append(&mut second_half);
+        first_half
+    }
+
+    fn loop_over_puzzle(&self, input: &Vec<String>, direction: Direction, rev: bool) -> Vec<String> {
+        let _input = if rev {
+            self._rotate(&self._rotate(&input))
+        } else {
+            input.clone()
+        };
+
+
+        match direction {
+            Direction::Horizontal => _input,
+            Direction::Vertical => self._mirror(&self._rotate(&_input)),
+            Direction::DiagonalUp => self.diagonal_loop(&_input),
+            Direction::DiagonalDown => self.diagonal_loop(&self._rotate(&_input)),
+        }
+    }
+}
+
+impl Day for Day4 {
+    fn example_input(&self) -> &'static str {
+        r#"
+        MMMSXXMASM
+        MSAMXMSMSA
+        AMXSXMAAMM
+        MSAMASMSMX
+        XMASAMXAMM
+        XXAMMXXAMA
+        SMSMSASXSS
+        SAXAMASAAA
+        MAMMMXMMMM
+        MXMXAXMASX
+        "#.trim()
+        // r#"
+        // 123
+        // 456
+        // 789
+        // "#.trim()
+    }
+
+    fn example_result_part_1(&self) -> &'static str {
+        "18"
+    }
+
+    fn example_result_part_2(&self) -> &'static str {
+        "9"
+    }
+
+    fn part_1(&self, input: BufReader<Box<dyn Read>>) -> String {
+        let puzzle = self.parse_input(input);
+
+        let mut all_possibilities: Vec<String> = vec![];
+
+        all_possibilities.append(&mut self.loop_over_puzzle(&puzzle, Direction::Horizontal, false));
+        all_possibilities.append(&mut self.loop_over_puzzle(&puzzle, Direction::Horizontal, true));
+        all_possibilities.append(&mut self.loop_over_puzzle(&puzzle, Direction::Vertical, false));
+        all_possibilities.append(&mut self.loop_over_puzzle(&puzzle, Direction::Vertical, true));
+        all_possibilities.append(&mut self.loop_over_puzzle(&puzzle, Direction::DiagonalUp, false));
+        all_possibilities.append(&mut self.loop_over_puzzle(&puzzle, Direction::DiagonalUp, true));
+        all_possibilities.append(&mut self.loop_over_puzzle(&puzzle, Direction::DiagonalDown, false));
+        all_possibilities.append(&mut self.loop_over_puzzle(&puzzle, Direction::DiagonalDown, true));
+
+        let re = Regex::new("XMAS");
+        all_possibilities
+            .into_iter()
+            .map(|l| {
+                re
+                    .clone()
+                    .unwrap()
+                    .find_iter(&l)
+                    .count()
+            })
+            .sum::<usize>()
+            .to_string()
+    }
+
+    fn part_2(&self, input: BufReader<Box<dyn Read>>) -> String {
+        let puzzle = self.parse_input(input);
+
+        let mut all_possibilities: Vec<String> = vec![];
+
+        all_possibilities.append(&mut self.loop_over_puzzle(&puzzle, Direction::DiagonalUp, false));
+        all_possibilities.append(&mut self.loop_over_puzzle(&puzzle, Direction::DiagonalDown, false));
+
+        let re = Regex::new("MAS|SAM");
+        all_possibilities
+            .into_iter()
+            .map(|l| {
+                re
+                    .clone()
+                    .unwrap()
+                    .find_iter(&l)
+                    .map(|m| println!("{:#?}", m))
+                    .count()
+            })
+            .sum::<usize>()
+            .to_string()
+    }
+}
+
+
+fn main() {
+    aoc::main(&Day4 {});
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_day4() {
+        aoc::test_day(&Day4 {});