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use std::{cmp::max, collections::HashSet, cmp::min};
use crate::coords::Cube;
pub trait Range {
fn range(&self, r: u8) -> HashSet<Self> where Self: Sized;
}
impl Range for Cube {
fn range(&self, r: u8) -> HashSet<Cube> {
let mut in_range = HashSet::with_capacity(hex_range_size(r));
for x in -(r as i8)..=r as i8 {
for y in max(-(r as i8), -x - r as i8)..=min(r as i8, -x + r as i8) {
in_range.insert(Cube(
self.0 + x,
self.1 + y,
self.2 + (-x - y)
));
}
}
in_range
}
}
fn hex_range_size(r: u8) -> usize {
(1 + 6 * r * (r + 1) / 2) as usize
}
#[cfg(test)]
mod test {
use super::*;
use crate::coords::Cube;
use crate::distance::Distance;
#[test]
fn hex_range_size_cases() {
assert_eq!(1, hex_range_size(0));
assert_eq!(7, hex_range_size(1));
assert_eq!(19, hex_range_size(2));
assert_eq!(37, hex_range_size(3));
}
#[test]
fn range_case_0() {
let center = Cube(0, 0, 0);
let radius = 3;
let range = center.range(radius);
verify_range(range, center, radius);
}
#[test]
fn range_case_1() {
let center = Cube(2, 1, -3);
let radius = 5;
let range = center.range(radius);
verify_range(range, center, radius);
}
fn verify_range(range: HashSet<Cube>, center: Cube, radius: u8) {
assert_eq!(hex_range_size(radius), range.len());
assert!(range.contains(¢er));
for x in range {
assert!(x.dist(¢er) <= radius);
}
}
}