Refactor

1 files changed, 96 insertions, 93 deletions

diff --git a/2024_rust/src/day4.rs b/2024_rust/src/day4.rs
index 1ebe67b..448fe19 100644
--- a/2024_rust/src/day4.rs
+++ b/2024_rust/src/day4.rs
@@ -1,69 +1,104 @@
 const XMAS: &str = "XMAS";
 const MAS: &str = "MAS";
 
-type Matrix = Vec<Vec<char>>;
 type Position = (usize, usize);
-type RowXmas = [Position; XMAS.len()];
-type RowMas = [Position; MAS.len()];
-
-fn check_xmas<'a, I>(m: &Matrix, it: I) -> bool
-where
-    I: Iterator<Item = &'a Position>,
-{
-    for (c, (i, j)) in XMAS.chars().zip(it) {
-        if m[*i][*j] != c {
-            return false;
+type Row = Vec<Position>;
+type Rows = Vec<Row>;
+type Move = (Position, (usize, isize));
+
+struct Matrix {
+    chars: Vec<Vec<char>>,
+    limit: Position,
+}
+
+impl Matrix {
+    fn new(text: &str) -> Self {
+        let chars: Vec<Vec<char>> = text.lines().map(|row| row.chars().collect()).collect();
+        let limit = (chars.len(), chars[0].len());
+        Self { chars, limit }
+    }
+
+    fn check_iter<'a, I>(&self, it: I, needle: &str) -> bool
+    where
+        I: Iterator<Item = &'a Position>,
+    {
+        for (c, (i, j)) in needle.chars().zip(it) {
+            if self.chars[*i][*j] != c {
+                return false;
+            }
         }
+
+        true
     }
 
-    true
+    fn check_row(&self, row: &Row, needle: &str) -> bool {
+        self.check_iter(row.iter(), needle) || self.check_iter(row.iter().rev(), needle)
+    }
 }
 
-fn offplus(x: usize, y: isize) -> usize {
-    (x as isize + y) as usize
+struct Square<'a> {
+    pos: Position,
+    size: usize,
+    matrix: &'a Matrix,
 }
 
-fn rows_latdiag_from(p: Position, max_x: usize, max_y: usize) -> Vec<RowXmas> {
-    let mut rs: Vec<RowXmas> = vec![];
-
-    // Horizontal / vertical / diagonal
-    for (p0, (di, dj)) in [
-        (p, (0, 1)),                                   // horizontal, left-to-right
-        (p, (1, 0)),                                   // vertical, top-down
-        (p, (1, 1)),                                   // diag from p, top-down and left-to-right
-        ((p.0, p.1 + XMAS.len() - 1), (1, -1isize)), // the other diag, top-down and right-to-left
-    ] {
-        // Bounds check
-        let max_off = XMAS.len();
-        if p0.0 + di * max_off > max_x
-            || (dj > 0 && offplus(p0.1, dj * max_off as isize) > max_y)
-            || p0.1 >= max_y
-        {
-            continue;
-        }
+impl Square<'_> {
+    fn rows<M>(&self, moves: M) -> Rows
+    where
+        M: Fn(&Square) -> Vec<Move>,
+    {
+        let mut rs: Rows = vec![];
+
+        // Horizontal / vertical / diagonal
+        for (p0, (di, dj)) in moves(self) {
+            // Bounds check
+            if p0.0 + di * self.size > self.matrix.limit.0
+                || (dj > 0 && offplus(p0.1, dj * self.size as isize) > self.matrix.limit.1)
+                || p0.1 >= self.matrix.limit.1
+            {
+                continue;
+            }
 
-        let mut p_acc = p0;
-        let mut ps = [(0, 0); XMAS.len()];
-        for idx in 0..ps.len() {
-            ps[idx].0 = p_acc.0;
-            ps[idx].1 = p_acc.1;
-            p_acc = (p_acc.0 + di, offplus(p_acc.1, dj));
+            let mut p_acc = p0;
+            let mut row: Row = vec![];
+            for _idx in 0..self.size {
+                row.push(p_acc);
+                p_acc = (p_acc.0 + di, offplus(p_acc.1, dj));
+            }
+            rs.push(row);
         }
-        rs.push(ps);
+
+        rs
     }
+}
 
-    rs
+fn offplus(x: usize, y: isize) -> usize {
+    (x as isize + y) as usize
+}
+
+fn moves_xmas(Square { pos, size, .. }: &Square) -> Vec<Move> {
+    let v = vec![
+        (*pos, (0, 1)),                       // diag from pos, top-down and left-to-right
+        (*pos, (1, 0)),                       // diag from pos, top-down and left-to-right
+        (*pos, (1, 1)),                       // diag from pos, top-down and left-to-right
+        ((pos.0, pos.1 + size - 1), (1, -1)), // the other diag, top-down and right-to-left
+    ];
+    v
 }
 
 pub fn p1(input: &str) -> String {
-    let m: Matrix = input.lines().map(|row| row.chars().collect()).collect();
+    let matrix: Matrix = Matrix::new(input);
     let mut result = 0;
 
-    for i in 0..m.len() {
-        for j in 0..m[i].len() {
-            let p = (i, j);
-            for row in rows_latdiag_from(p, m.len(), m[i].len()) {
-                if check_xmas(&m, row.iter()) || check_xmas(&m, row.iter().rev()) {
+    for i in 0..matrix.limit.0 {
+        for j in 0..matrix.limit.1 {
+            let sq = Square {
+                pos: (i, j),
+                size: XMAS.len(),
+                matrix: &matrix,
+            };
+            for row in sq.rows(moves_xmas) {
+                if matrix.check_row(&row, XMAS) {
                     result += 1;
                 }
             }
@@ -73,58 +108,26 @@ pub fn p1(input: &str) -> String {
     result.to_string()
 }
 
-fn check_mas<'a, I>(m: &Matrix, it: I) -> bool
-where
-    I: Iterator<Item = &'a Position>,
-{
-    for (c, (i, j)) in MAS.chars().zip(it) {
-        if m[*i][*j] != c {
-            return false;
-        }
-    }
-
-    true
-}
-
-fn rows_diag_from(p: Position, max_x: usize, max_y: usize) -> Vec<RowMas> {
-    let mut rs: Vec<RowMas> = vec![];
-
-    // Horizontal / vertical / diagonal
-    for (p0, (di, dj)) in [
-        (p, (1, 1)),                                   // diag from p, top-down and left-to-right
-        ((p.0, p.1 + MAS.len() - 1), (1, -1isize)), // the other diag, top-down and right-to-left
-    ] {
-        // Bounds check
-        let max_off = MAS.len();
-        if p0.0 + di * max_off > max_x
-            || (dj > 0 && offplus(p0.1, dj * max_off as isize) > max_y)
-            || p0.1 >= max_y
-        {
-            continue;
-        }
-
-        let mut p_acc = p0;
-        let mut ps = [(0, 0); MAS.len()];
-        for idx in 0..ps.len() {
-            ps[idx].0 = p_acc.0;
-            ps[idx].1 = p_acc.1;
-            p_acc = (p_acc.0 + di, offplus(p_acc.1, dj));
-        }
-        rs.push(ps);
-    }
-
-    rs
+fn moves_mas(Square { pos, size, .. }: &Square) -> Vec<Move> {
+    let v = vec![
+        (*pos, (1, 1)),                       // diag from pos, top-down and left-to-right
+        ((pos.0, pos.1 + size - 1), (1, -1)), // the other diag, top-down and right-to-left
+    ];
+    v
 }
 
 pub fn p2(input: &str) -> String {
-    let m: Matrix = input.lines().map(|row| row.chars().collect()).collect();
+    let matrix: Matrix = Matrix::new(input);
     let mut result = 0;
 
-    for i in 0..=m.len() - MAS.len() {
-        for j in 0..=m[i].len() - MAS.len() {
-            let p = (i, j);
-            let rows = rows_diag_from(p, m.len(), m[i].len());
-            if rows.iter().all(|r| check_mas(&m, r.iter()) || check_mas(&m, r.iter().rev())) {
+    for i in 0..=matrix.limit.0 - MAS.len() {
+        for j in 0..=matrix.limit.1 - MAS.len() {
+            let sq = Square {
+                pos: (i, j),
+                size: MAS.len(),
+                matrix: &matrix,
+            };
+            if sq.rows(moves_mas).iter().all(|r| matrix.check_row(r, MAS)) {
                 result += 1;
             }
         }