finish 11

src/euler11/src/coordinate.rs

@@ -0,0 +1,39 @@
+use std::fmt::Debug;
+
+#[derive(PartialEq)]
+pub struct Coordinate {
+    pub x: usize,
+    pub y: usize,
+}
+
+impl Coordinate {
+    pub fn new(x: usize, y: usize) -> Self {
+        Self { x, y }
+    }
+
+    pub fn from_coordinate_pairs(x_idxs: [usize; 4], y_idxs: [usize; 4]) -> [Self; 4] {
+        let result: Vec<_> = x_idxs
+            .iter()
+            .zip(y_idxs)
+            .map(|(x, y)| Self::new(*x, y))
+            .collect();
+        result.try_into().unwrap()
+    }
+}
+
+impl Debug for Coordinate {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let inner = &format!("{},{}", self.x, self.y);
+        f.write_str(inner)
+    }
+}
+
+pub trait Show {
+    fn show(&self) -> String;
+}
+
+impl Show for [Coordinate; 4] {
+    fn show(&self) -> String {
+        self.iter().map(|c| format!("{},{} --", c.x, c.y)).collect()
+    }
+}

src/euler11/src/direction.rs

@@ -0,0 +1,19 @@
+#[derive(Debug)]
+pub enum Direction {
+    Down,
+    Right,
+    DiagonalUp,
+    DiagonalDown,
+}
+
+impl Iterator for Direction {
+    type Item = (Self, bool);
+    fn next(&mut self) -> Option<Self::Item> {
+        match self {
+            Direction::Down => Some((Direction::Right, false)),
+            Direction::Right => Some((Direction::DiagonalUp, false)),
+            Direction::DiagonalUp => Some((Direction::DiagonalDown, false)),
+            Direction::DiagonalDown => Some((Direction::Down, true)),
+        }
+    }
+}

src/euler11/src/grid.rs

@@ -0,0 +1,37 @@
+use crate::neighbours::Neighbours;
+
+type Data = u32;
+
+pub struct Grid {
+    grid: Vec<Vec<Data>>,
+    neighbours: Neighbours,
+}
+
+impl Grid {
+    pub fn from_file(filename: &str) -> Self {
+        let grid: Vec<Vec<_>> = std::fs::read_to_string(filename)
+            .unwrap()
+            .split_terminator('\n')
+            .map(|line| {
+                line.split_whitespace()
+                    .map(|cell| cell.parse::<u8>().unwrap() as Data)
+                    .collect()
+            })
+            .collect();
+        let ny = grid.len();
+        let nx = grid[0].len();
+        let neighbours = Neighbours::new(nx, ny);
+        Grid { grid, neighbours }
+    }
+
+    pub fn run(&mut self) {
+        let mut largest = 0;
+        while let Some(coordinates) = self.neighbours.next() {
+            let value = coordinates.iter().map(|c| self.grid[c.y][c.x]).product();
+            if value > largest {
+                largest = value;
+            }
+        }
+        println!("{largest}");
+    }
+}

src/euler11/src/main.rs

@@ -1,190 +1,9 @@
-use std::{fmt::Debug, fs};
+mod coordinate;
+mod direction;
+mod grid;
+mod neighbours;
 
-const LENGTH: usize = 4;
-
-type Data = u32;
-type Neighbours = Vec<Coordinate>;
-
-struct Coordinate {
-    x: usize,
-    y: usize,
-}
-
-impl Coordinate {
-    fn new(x: usize, y: usize) -> Self {
-        Self { x, y }
-    }
-}
-
-impl Debug for Coordinate {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        let inner = &format!("{},{}", self.x, self.y);
-        f.write_str(inner)
-    }
-}
-
-struct Grid {
-    grid: Vec<Vec<Data>>,
-    nx: usize,
-    ny: usize,
-    curr_x: usize,
-    curr_y: usize,
-    curr_direction: Direction,
-    done: bool,
-}
-
-impl Grid {
-    fn from_file(filename: &str) -> Self {
-        let grid: Vec<Vec<_>> = fs::read_to_string(filename)
-            .unwrap()
-            .split_terminator('\n')
-            .map(|line| {
-                line.split_whitespace()
-                    .map(|cell| cell.parse::<u8>().unwrap() as Data)
-                    .collect()
-            })
-            .collect();
-        let ny = grid.len();
-        let nx = grid[0].len();
-        Grid {
-            grid,
-            nx,
-            ny,
-            curr_x: 0,
-            curr_y: 0,
-            curr_direction: Direction::None,
-            done: false,
-        }
-    }
-
-    fn run(&mut self) {
-        let mut largest = 0;
-        loop {
-            if let Some(coordinates) = self.next() {
-                let value = coordinates.iter().map(|c| self.grid[c.y][c.x]).product();
-                if value > largest {
-                    largest = value;
-                }
-            }
-            if self.done {
-                break;
-            }
-        }
-        println!("{largest}");
-    }
-
-    fn advance_index(&mut self) {
-        if self.curr_x == self.nx - 1 {
-            self.curr_x = 0;
-            self.curr_y += 1;
-            if self.curr_y == self.ny {
-                self.done = true;
-            }
-        } else {
-            self.curr_x += 1;
-        }
-    }
-
-    fn get_neighbours(&self) -> Option<Neighbours> {
-        match self.curr_direction {
-            Direction::Down => self.get_neighbours_down(),
-            Direction::Right => self.get_neighbours_right(),
-            Direction::DiagonalUp => self.get_neighbours_diag_up(),
-            Direction::DiagonalDown => self.get_neighbours_diag_down(),
-            Direction::None => unreachable!(),
-        }
-    }
-
-    fn get_neighbours_down(&self) -> Option<Neighbours> {
-        let max_y = self.curr_y + LENGTH;
-        if max_y > self.ny {
-            None
-        } else {
-            Some(
-                (self.curr_y..max_y)
-                    .map(|y| Coordinate::new(self.curr_x, y))
-                    .collect(),
-            )
-        }
-    }
-
-    fn get_neighbours_right(&self) -> Option<Neighbours> {
-        let max_x = self.curr_x + LENGTH;
-        if max_x > self.nx {
-            None
-        } else {
-            Some(
-                (self.curr_x..max_x)
-                    .map(|x| Coordinate::new(x, self.curr_y))
-                    .collect(),
-            )
-        }
-    }
-
-    fn get_neighbours_diag_up(&self) -> Option<Neighbours> {
-        let max_x = self.curr_x + LENGTH;
-        let min_y = self.curr_y.wrapping_sub(LENGTH);
-        if max_x > self.nx || min_y > self.ny {
-            None
-        } else {
-            Some(
-                (self.curr_x..max_x)
-                    .zip(self.curr_y..min_y)
-                    .map(|(x, y)| Coordinate::new(x, y))
-                    .collect(),
-            )
-        }
-    }
-
-    fn get_neighbours_diag_down(&self) -> Option<Neighbours> {
-        let max_x = self.curr_x + LENGTH;
-        let max_y = self.curr_y + LENGTH;
-        if max_x > self.nx || max_y > self.ny {
-            None
-        } else {
-            Some(
-                (self.curr_x..max_x)
-                    .zip(self.curr_y..max_y)
-                    .map(|(x, y)| Coordinate::new(x, y))
-                    .collect(),
-            )
-        }
-    }
-}
-
-impl Iterator for Grid {
-    type Item = Neighbours;
-
-    fn next(&mut self) -> Option<Self::Item> {
-        let has_wrapped;
-        (self.curr_direction, has_wrapped) = self.curr_direction.next();
-        if has_wrapped {
-            self.advance_index();
-        };
-        self.get_neighbours()
-    }
-}
-
-#[derive(Debug)]
-enum Direction {
-    None,
-    Down,
-    Right,
-    DiagonalUp,
-    DiagonalDown,
-}
-
-impl Direction {
-    fn next(&self) -> (Self, bool) {
-        match self {
-            Direction::None => (Direction::Down, false),
-            Direction::Down => (Direction::Right, false),
-            Direction::Right => (Direction::DiagonalUp, false),
-            Direction::DiagonalUp => (Direction::DiagonalDown, false),
-            Direction::DiagonalDown => (Direction::Down, true),
-        }
-    }
-}
+use grid::Grid;
 
 fn main() {
     let mut grid = Grid::from_file("grid.txt");

src/euler11/src/neighbours.rs

@@ -0,0 +1,107 @@
+use crate::coordinate::Coordinate;
+use crate::direction::Direction;
+
+const LENGTH: usize = 4;
+
+pub struct Neighbours {
+    nx: usize,
+    ny: usize,
+    x: usize,
+    y: usize,
+    current_direction: Direction,
+    done: bool,
+}
+
+impl Neighbours {
+    pub fn new(nx: usize, ny: usize) -> Self {
+        Self {
+            nx,
+            ny,
+            x: 0,
+            y: 0,
+            current_direction: Direction::Down,
+            done: false,
+        }
+    }
+
+    fn iterate_direction(&mut self) {
+        let (new_direction, has_wrapped) = self.current_direction.next().unwrap();
+        self.current_direction = new_direction;
+        if has_wrapped {
+            self.x += 1;
+            if self.x == self.nx {
+                self.x = 0;
+                self.y += 1;
+                if self.y == self.ny {
+                    self.done = true;
+                }
+            }
+        }
+    }
+}
+
+impl Iterator for Neighbours {
+    type Item = [Coordinate; 4];
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.done {
+            return None;
+        }
+
+        let x = self.x;
+        let y = self.y;
+
+        let x_idxs;
+        let y_idxs;
+
+        match self.current_direction {
+            Direction::Down => {
+                x_idxs = [x; 4];
+                y_idxs = [y, y + 1, y + 2, y + 3];
+            }
+            Direction::Right => {
+                x_idxs = [x, x + 1, x + 2, x + 3];
+                y_idxs = [y; 4];
+            }
+            Direction::DiagonalUp => {
+                if y < LENGTH {
+                    self.iterate_direction();
+                    return self.next();
+                }
+                x_idxs = [x, x + 1, x + 2, x + 3];
+                y_idxs = [y, y - 1, y - 2, y - 3];
+            }
+            Direction::DiagonalDown => {
+                x_idxs = [x, x + 1, x + 2, x + 3];
+                y_idxs = [y, y + 1, y + 2, y + 3];
+            }
+        }
+
+        if x_idxs.iter().any(|x| *x >= self.nx) || y_idxs.iter().any(|y| *y >= self.ny) {
+            self.iterate_direction();
+            return self.next();
+        }
+
+        let result = Coordinate::from_coordinate_pairs(x_idxs, y_idxs);
+
+        self.iterate_direction();
+
+        Some(result)
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::Neighbours;
+    use crate::coordinate::Coordinate as C;
+
+    #[test]
+    fn neighbours() {
+        let mut n = Neighbours::new(20, 20);
+        n.next()
+            .unwrap()
+            .iter()
+            .zip([C::new(0, 0), C::new(0, 1), C::new(0, 2), C::new(0, 3)])
+            .for_each(|(c1, c2)| assert_eq!(*c1, c2));
+    }
+}