dag 4 aoc, deed meer dan verwacht werd, wat ervoor zorgde dat ik teveel kruizen telde

advent_of_code/2024/4/src/main.rs

@@ -0,0 +1,153 @@
+use std::cmp::{max, min};
+
+fn parse(input: &str) -> Vec<Vec<char>> {
+    input.lines().map(|s| s.chars().collect()).collect()
+}
+
+fn check_xmas(chars: &Vec<Vec<char>>, start: &(i32, i32), direction: (i32, i32)) -> bool {
+    let h = chars.len() as i32;
+    let w = chars[0].len() as i32;
+
+    if start.0 + 3 * direction.0 < 0
+        || start.0 + 3 * direction.0 >= w
+        || start.1 + 3 * direction.1 < 0
+        || start.1 + 3 * direction.1 >= h
+    {
+        return false;
+    }
+
+    let xmas = vec!['X', 'M', 'A', 'S'];
+
+    for x in 0..4 {
+        let cur_pos = (start.0 + x * direction.0, start.1 + x * direction.1);
+
+        if chars[cur_pos.1 as usize][cur_pos.0 as usize] != xmas[x as usize] {
+            return false;
+        }
+    }
+
+    true
+}
+
+fn solve_1(input: &str) -> usize {
+    let input = parse(input);
+
+    let h = input.len() as i32;
+    let w = input[0].len() as i32;
+
+    let mut result = 0;
+
+    for j in 0..h {
+        for i in 0..w {
+            if input[j as usize][i as usize] == 'X' {
+                for ii in max(0, i - 1)..=min(i + 1, w - 1) {
+                    for jj in max(0, j - 1)..=min(j + 1, h - 1) {
+                        if input[jj as usize][ii as usize] == 'M' {
+                            let dir = (ii - i, jj - j);
+
+                            if check_xmas(&input, &(i, j), dir) {
+                                result += 1;
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    result
+}
+
+fn check_x_mas(chars: &Vec<Vec<char>>, candidate: (i32, i32)) -> usize {
+    let h = chars.len() as i32;
+    let w = chars[0].len() as i32;
+    let (x, y) = candidate;
+
+    if x == 0 || x == w - 1 || y == 0 || y == h - 1 {
+        return 0;
+    }
+
+    let mut result = 0;
+
+    let mut diagonal_ms = vec![];
+    let mut diagonal_ss = vec![];
+    for i in 0..2 {
+        for j in 0..2 {
+            let coord = (x as usize - 1 + 2 * i, y as usize - 1 + 2 * j);
+            match chars[coord.1][coord.0] {
+                'M' => diagonal_ms.push(coord),
+                'S' => diagonal_ss.push(coord),
+                _ => (),
+            }
+        }
+    }
+    if diagonal_ms.len() >= 2 && diagonal_ss.len() >= 2 {
+        if diagonal_ms
+            .into_iter()
+            .filter(|&(cx, cy)| {
+                let x_diff = cx as i32 - candidate.0;
+                let y_diff = cy as i32 - candidate.1;
+
+                diagonal_ss.contains(&(
+                    (candidate.0 - x_diff) as usize,
+                    (candidate.1 - y_diff) as usize,
+                ))
+            })
+            .count()
+            == 2
+        {
+            result += 1;
+        }
+    }
+
+    result
+}
+
+fn solve_2(input: &str) -> usize {
+    let input = parse(input);
+
+    let h = input.len() as i32;
+    let w = input[0].len() as i32;
+
+    let mut result = 0;
+
+    for j in 0..h {
+        for i in 0..w {
+            if input[j as usize][i as usize] == 'A' {
+                result += check_x_mas(&input, (i, j));
+            }
+        }
+    }
+
+    result
+}
+
+fn main() {
+    println!("Hello, this is Patrick!");
+
+    let input = include_str!("../input.txt");
+
+    let result_1 = solve_1(input);
+    println!("The number of XMASs is {}", result_1);
+
+    let result_2 = solve_2(input);
+    println!("The number of X-MASs is {}", result_2);
+}
+
+#[cfg(test)]
+
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1() {
+        let test_input = include_str!("../test.txt");
+        assert_eq!(solve_1(test_input), 18);
+    }
+
+    #[test]
+    fn test_2() {
+        let test_input = include_str!("../test.txt");
+        assert_eq!(solve_2(test_input), 9);
+    }
+}