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day10 task 1

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Johannes
2019-12-11 18:07:39 +01:00
parent d3ef4235a0
commit 0f17084f18
2 changed files with 45 additions and 22 deletions
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38
src/tasks/day10.rs
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@@ -21,7 +21,7 @@ fn task1(asteroids: &HashSet<(i32, i32)>) {
let max = asteroids
.iter()
.map(|asteroid| {
//println!("inspecting {:?}", asteroid);
println!("inspecting {:?}", asteroid);
// map to number of other asteroids it sees
let mut others = asteroids.clone();
others.remove(&asteroid);
@@ -29,11 +29,15 @@ fn task1(asteroids: &HashSet<(i32, i32)>) {
let count = others
.iter()
.filter(|target| {
!others
let blocker = others
.iter()
.any(|occluder| blocks_view(*asteroid, **target, *occluder))
.find(|occluder| blocks_view(*asteroid, **target, **occluder));
if let Some(occluder) = blocker {
println!("{:?} -> X{:?}X -> {:?}", asteroid, occluder, target);
}
!blocker.is_some()
})
//.inspect(|target| println!("sees {:?}", target))
.inspect(|target| println!("sees {:?}", target))
.count();
println!("{:?}: {}", asteroid, count);
count
@@ -43,29 +47,29 @@ fn task1(asteroids: &HashSet<(i32, i32)>) {
println!(
"Task 1: maximum visible asteroids from another asteroid are {}",
max
); //283 too high, 257 too low
);
}
fn blocks_view(pov: (i32, i32), target: (i32, i32), occluder: (i32, i32)) -> bool {
let ux = occluder.0 - pov.0;
let uy = occluder.1 - pov.1;
let sx = (target.0 - pov.0) as f32 / ux as f32;
let sy = (target.1 - pov.1) as f32 / uy as f32;
//dbg!((ux, uy, sx, sy));
match (ux, uy) {
(0, _) => sy.abs() > 1.0 && target.0 == pov.0,
(_, 0) => sx.abs() > 1.0 && target.1 == pov.1,
(_, _) => sx.abs() > 1.0 && sx == sy,
if occluder == target {
return false;
}
fn d(a: (i32, i32), b: (i32, i32)) -> f32 {
((a.0 - b.0) as f32).powi(2) + ((a.1 - b.1) as f32).powi(2).sqrt()
}
// using polar coordinates
let alpha_occluder = ((occluder.1 - pov.1) as f32).atan2((occluder.0 - pov.0) as f32);
let alpha_target = ((target.1 - pov.1) as f32).atan2((target.0 - pov.0) as f32);
(alpha_occluder - alpha_target).abs() <= std::f32::EPSILON && d(pov, target) > d(pov, occluder)
}
mod test {
#[test]
fn block_test() {
assert_eq!(true, super::blocks_view((3, 4), (1, 0), (2, 2)));
assert_ne!(true, super::blocks_view((3, 4), (2, 2), (1, 0)));
assert_ne!(true, super::blocks_view((3, 4), (1, 0), (1, 2)));
assert_eq!(false, super::blocks_view((3, 4), (2, 2), (1, 0)));
assert_eq!(false, super::blocks_view((3, 4), (1, 0), (1, 2)));
assert_eq!(true, super::blocks_view((4, 4), (4, 0), (4, 3)));
assert_eq!(false, super::blocks_view((3, 2), (1, 0), (4, 3)));
}
}