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#[derive(Debug)]
pub struct Grid<T> {
grid: Vec<Vec<T>>,
}
impl<T> Grid<T> {
pub fn new(grid: Vec<Vec<T>>) -> Grid<T> {
Grid { grid }
}
pub fn points(&self) -> impl Iterator<Item = (usize, usize)> {
(0..self.grid.len())
.flat_map(|y| (0..self.grid.first().unwrap_or(&Vec::new()).len()).map(move |x| (x, y)))
}
pub fn ray(&self, (x, y): (usize, usize), (dx, dy): (i64, i64)) -> impl Iterator<Item = &T> {
let (x, y) = (i64::try_from(x).unwrap(), i64::try_from(y).unwrap());
(0..)
.map(move |n| {
self.grid
.get(usize::try_from(y + n * dy).ok()?)
.and_then(|row| row.get(usize::try_from(x + n * dx).ok()?))
})
.take_while(Option::is_some)
.flatten()
}
}
#[cfg(test)]
mod tests {
use std::collections::HashSet;
use super::*;
#[test]
fn create_grid() {
let _grid = Grid::new(vec![vec![1, 2, 3], vec![4, 5, 6], vec![7, 8, 9]]);
}
#[test]
fn points_empty() {
let grid = Grid::<u64>::new(vec![vec![]]);
assert!(grid.points().eq(vec![]))
}
#[test]
fn points_equal_size() {
let grid = Grid::new(vec![vec![1, 2], vec![3, 4]]);
let points = grid.points().collect::<HashSet<_>>();
assert_eq!(
points,
[(0, 0), (0, 1), (1, 0), (1, 1)].iter().cloned().collect()
)
}
#[test]
fn points_unequal_size() {
let grid = Grid::new(vec![vec![1, 2], vec![3, 4], vec![5, 6]]);
let points = grid.points().collect::<HashSet<_>>();
assert_eq!(
points,
[(0, 0), (1, 0), (0, 1), (1, 1), (0, 2), (1, 2)]
.iter()
.cloned()
.collect()
)
}
#[test]
fn ray_empty() {
let grid = Grid::<u64>::new(vec![vec![]]);
assert!(grid.ray((1, 1), (1, 2)).eq(vec![].iter()))
}
#[test]
fn ray_single_element() {
let grid = Grid::<u64>::new(vec![vec![1]]);
assert!(grid.ray((0, 0), (1, 2)).eq(vec![1].iter()))
}
#[test]
fn ray_horizontal() {
let grid = Grid::new(vec![vec![1, 2, 3], vec![4, 5, 6], vec![7, 8, 9]]);
assert!(grid.ray((0, 0), (1, 0)).eq(vec![1, 2, 3].iter()))
}
#[test]
fn ray_vertical() {
let grid = Grid::new(vec![vec![1, 2, 3], vec![4, 5, 6], vec![7, 8, 9]]);
assert!(grid.ray((1, 0), (0, 1)).eq(vec![2, 5, 8].iter()))
}
#[test]
fn ray_diagonal() {
let grid = Grid::new(vec![vec![1, 2, 3], vec![4, 5, 6], vec![7, 8, 9]]);
assert!(grid.ray((0, 0), (1, 2)).eq(vec![1, 8].iter()))
}
}
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