🚧 WIP on Day 4

I don't have enough time in the morning...

src/days/d04.rs

@@ -2,31 +2,140 @@ use super::{Answer, Day, DayImpl};
 
 const CURRENT_DAY: u8 = 4;
 
-type Data = Vec<u64>;
+#[derive(Debug, Clone,Copy)]
+enum Direction {
+    East,
+    West,
+    North,
+    South,
+    NorthEast,
+    NorthWest,
+    SouthEast,
+    SouthWest
+}
+
+#[derive(Debug, Clone)]
+pub struct LetterWall (Vec<Vec<char>>);
+
+impl LetterWall {
+    fn at(&self, x: usize, y: usize) -> Option<&char> {
+        let row = self.0.get(y);
+
+        if let Some(row) = row {
+            row.get(x)
+        } else {
+            None
+        }
+    }
+
+    pub fn is_upper_left_of_xmas(&self, x: usize, y: usize) -> Option<Direction> {
+        match(
+            self.at( x, y), self.at( x+1, y), self.at( x+2, y), self.at( x+3, y),
+            self.at( x, y+1), self.at( x+1, y+1), self.at( x+2, y+1), self.at( x+3, y+1),
+            self.at( x, y+2), self.at( x+1, y+2), self.at( x+2, y+2), self.at( x+3, y+2),
+            self.at( x, y+3), self.at( x+1, y+3), self.at( x+2, y+3), self.at( x+3, y+3)
+        ) {
+            (
+                Some('X'), Some('M'), Some('A'), Some('S'),
+                _, _, _, _,
+                _, _, _, _,
+                _, _, _, _
+            ) => Some(Direction::East),
+            (
+                Some('S'), Some('A'), Some('M'), Some('X'),
+                _, _, _, _,
+                _, _, _, _,
+                _, _, _, _
+            ) => Some(Direction::West),
+            (
+                Some('X'), _, _, _,
+                Some('M'), _, _, _,
+                Some('A'), _, _, _,
+                Some('S'), _, _, _
+            ) => Some(Direction::South),
+            (
+                Some('S'), _, _, _,
+                Some('A'), _, _, _,
+                Some('M'), _, _, _,
+                Some('X'), _, _, _
+            ) => Some(Direction::North),
+            (
+                Some('X'), _, _, _,
+                _, Some('M'), _, _,
+                _, _, Some('A'), _,
+                _, _, _, Some('S')
+            ) => Some(Direction::SouthEast),
+            (
+                Some('S'), _, _, _,
+                _, Some('A'), _, _,
+                _, _, Some('M'), _,
+                _, _, _, Some('X')
+            ) => Some(Direction::NorthWest),
+            (
+                _, _, _, Some('X'),
+                _, _, Some('M'), _,
+                _, Some('A'), _, _,
+                Some('S'), _, _, _
+            ) => Some(Direction::SouthWest),
+            (
+                _, _, _, Some('S'),
+                _, _, Some('A'), _,
+                _, Some('M'), _, _,
+                Some('X'), _, _, _
+            ) => Some(Direction::SouthWest),
+            _ => None
+        }
+    }
+
+    pub fn count_xmas(&self) -> u64 {
+        let mut count = 0;
+        for y in 0..self.0.len(){
+            for x in 0..self.0[0].len() {
+                if let Some(dir) = self.is_upper_left_of_xmas(x, y) {
+                    println!("FOUND AT {} {} '{}' - DIR: {:?}", x, y, self.0[y][x], dir);
+                    count += 1;
+                }
+            }
+        }
+        return count;
+    }
+}
+
+impl From<&str> for LetterWall {
+    fn from(value: &str) -> Self {
+        Self (
+            value
+                .lines()
+                .map(|v| v.chars().collect())
+                .collect()
+        )
+    }
+}
+
+type Data = LetterWall;
+
 impl DayImpl<Data> for Day<CURRENT_DAY> {
     fn init_test() -> (Self, Data) {
         Self::init(include_str!("test_inputs/test04.txt"))
     }
 
     fn expected_results() -> (Answer, Answer) {
-        (Answer::Number(0), Answer::Number(0))
+        (Answer::Number(18), Answer::Number(0))
     }
 
     fn init(input: &str) -> (Self, Data) {
         (
             Self {},
-            input
-                .lines()
-                .map(|v| v.parse::<u64>().expect("error while parsing input."))
-                .collect(),
+            input.into(),
         )
     }
 
     fn one(&self, data: &mut Data) -> Answer {
-        Answer::Number(data.len() as u64)
+        // NOTE TO SELF: Actual result above 2334
+        Answer::Number(data.count_xmas())
     }
 
     fn two(&self, data: &mut Data) -> Answer {
-        Answer::Number(data.len() as u64)
+        Answer::Number(0)
     }
 }

src/days/test_inputs/test04.txt

@@ -0,0 +1,10 @@
+MMMSXXMASM
+MSAMXMSMSA
+AMXSXMAAMM
+MSAMASMSMX
+XMASAMXAMM
+XXAMMXXAMA
+SMSMSASXSS
+SAXAMASAAA
+MAMMMXMMMM
+MXMXAXMASX