day12
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2 changed files with 337 additions and 1 deletions
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@ -36,4 +36,8 @@ path = "src/day9/main.rs"
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[[bin]]
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name = "day10"
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path = "src/day10/main.rs"
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path = "src/day10/main.rs"
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[[bin]]
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name = "day12"
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path = "src/day12/main.rs"
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332
src/day12/main.rs
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332
src/day12/main.rs
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@ -0,0 +1,332 @@
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use std::cmp::Ordering;
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use std::collections::hash_map::DefaultHasher;
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use std::collections::HashMap;
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use std::hash::{Hash, Hasher};
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use std::iter::FromIterator;
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#[derive(PartialEq, Debug, Default, Clone, Hash)]
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struct Object {
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x: isize,
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y: isize,
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z: isize,
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}
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impl From<(isize, isize, isize)> for Object {
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fn from(o: (isize, isize, isize)) -> Self {
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Object {
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x: o.0,
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y: o.1,
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z: o.2,
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}
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}
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}
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impl Object {
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fn attract(&self, other: &Object, v: &mut Object) {
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v.x += Object::cmp(self.x, other.x);
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v.y += Object::cmp(self.y, other.y);
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v.z += Object::cmp(self.z, other.z);
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}
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fn apply(&mut self, v: &Object) {
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self.x += v.x;
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self.y += v.y;
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self.z += v.z;
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}
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fn cmp(a: isize, b: isize) -> isize {
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match b.cmp(&a) {
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Ordering::Less => -1,
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Ordering::Equal => 0,
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Ordering::Greater => 1,
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}
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}
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fn energy(&self) -> usize {
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return (self.x.abs() + self.y.abs() + self.z.abs()) as usize;
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}
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}
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struct Space {
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iteration: u128,
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moons: Vec<Object>,
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velocy: Vec<Object>,
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}
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impl From<Vec<Object>> for Space {
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fn from(moons: Vec<Object>) -> Self {
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let iteration = 0;
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let velocy = Vec::from_iter((0..moons.len()).map(|_| Object::default()));
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Space {
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iteration,
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moons,
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velocy,
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}
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}
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}
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impl Hash for Space {
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fn hash<H: Hasher>(&self, state: &mut H) {
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self.moons.iter().for_each(|m| m.hash(state));
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self.velocy.iter().for_each(|v| v.hash(state));
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}
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}
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impl Space {
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fn step(&mut self) {
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self.iteration += 1;
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let moons: &mut Vec<Object> = self.moons.as_mut();
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let velocy: &mut Vec<Object> = self.velocy.as_mut();
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moons.iter().enumerate().for_each(|(idx, a)| {
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moons.iter().for_each(|b| {
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if a == b {
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return;
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}
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a.attract(b, velocy.get_mut(idx).unwrap())
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})
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});
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moons
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.iter_mut()
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.enumerate()
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.for_each(|(idx, m)| m.apply(velocy.get(idx).unwrap()));
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}
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fn status(&self) -> impl Iterator<Item = (&'_ Object, &'_ Object)> {
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self.moons
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.iter()
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.zip(self.velocy.iter())
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.map(|(a, b)| (a, b))
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}
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fn iteration(&self) -> u128 {
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return self.iteration;
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}
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fn hashed(&self) -> u64 {
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let mut hash = DefaultHasher::new();
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self.hash(&mut hash);
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hash.finish()
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}
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fn reapeats(mut self) -> u128 {
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let mut known: HashMap<u64, u128> = HashMap::new();
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loop {
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println!("a lot");
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known.insert(self.hashed(), self.iteration());
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// 4686774924
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for _ in 0..10000000 {
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self.step();
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if let Some(iteration) = known.get(&self.hashed()) {
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let ago = self.iteration() - iteration;
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return ago;
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}
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}
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}
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}
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}
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#[derive(Eq, PartialEq, Clone)]
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struct Axis {
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p: isize,
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}
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impl From<isize> for Axis {
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fn from(p: isize) -> Self {
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Axis { p }
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}
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}
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impl Axis {
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fn attract(&self, other: &Axis, v: &mut Axis) {
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v.p += Axis::cmp(self.p, other.p);
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}
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fn apply(&mut self, v: &Axis) {
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self.p += v.p;
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}
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fn cmp(a: isize, b: isize) -> isize {
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match b.cmp(&a) {
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Ordering::Less => -1,
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Ordering::Equal => 0,
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Ordering::Greater => 1,
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}
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}
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fn energy(&self) -> usize {
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return self.p.abs() as usize;
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}
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}
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struct AxisSpace {
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iteration: usize,
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moons: Vec<Axis>,
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velocy: Vec<Axis>,
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}
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impl From<Vec<isize>> for AxisSpace {
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fn from(moons: Vec<isize>) -> Self {
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let iteration = 0;
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let moons = Vec::from_iter(moons.iter().map(|i| Axis::from(*i)));
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let velocy = Vec::from_iter((0..moons.len()).map(|_| Axis::from(0)));
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AxisSpace {
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iteration,
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moons,
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velocy,
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}
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}
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}
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impl AxisSpace {
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fn step(&mut self) {
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self.iteration += 1;
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let moons: &mut Vec<Axis> = self.moons.as_mut();
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let velocy: &mut Vec<Axis> = self.velocy.as_mut();
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moons.iter().enumerate().for_each(|(idx, a)| {
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moons.iter().for_each(|b| {
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if a == b {
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return;
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}
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a.attract(&b, &mut velocy[idx])
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})
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});
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moons
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.iter_mut()
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.enumerate()
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.for_each(|(idx, m)| m.apply(velocy.get(idx).unwrap()));
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}
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fn iteration(&self) -> usize {
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return self.iteration;
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}
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fn reapeats(mut self) -> usize {
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let want = self.moons.clone();
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self.step();
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while self.moons != want {
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self.step();
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}
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return self.iteration() + 1;
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}
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}
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fn gcd(x: usize, y: usize) -> usize {
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let mut x = x;
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let mut y = y;
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while y != 0 {
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let t = y;
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y = x % y;
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x = t;
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}
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x
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}
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fn lcm(a: usize, b: usize) -> usize {
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a * b / gcd(a, b)
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}
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fn lcm3(a: usize, b: usize, c: usize) -> usize {
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lcm(a, lcm(b, c))
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}
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fn main() {
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// part1
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let moons = vec![
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Object::from((17, 5, 1)),
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Object::from((-2, -8, 8)),
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Object::from((7, -6, 14)),
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Object::from((1, -10, 4)),
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];
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let mut space = Space::from(moons);
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let mut step_energy = 0;
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(1..=100).for_each(|_i| {
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(1..=10).for_each(|_| {
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space.step();
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});
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step_energy = space
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.status()
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.map(|(o, v)| o.energy() * v.energy())
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.fold(0, |mut acc, c| {
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acc += c;
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acc
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});
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});
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println!("energy: {}", step_energy);
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// part2
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let xspace = AxisSpace::from(vec![-1, 2, 4, 3]);
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let yspace = AxisSpace::from(vec![0, -10, -8, 5]);
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let zspace = AxisSpace::from(vec![2, -7, 8, -1]);
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let total = lcm3(xspace.reapeats(), yspace.reapeats(), zspace.reapeats());
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println!("matching space found {} iterations ago", total);
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let xspace = AxisSpace::from(vec![-8, 5, 2, 9]);
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let yspace = AxisSpace::from(vec![-10, 5, -7, -8]);
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let zspace = AxisSpace::from(vec![0, 10, 3, -3]);
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let total = lcm3(xspace.reapeats(), yspace.reapeats(), zspace.reapeats());
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println!("matching space found {} iterations ago", total);
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let xspace = AxisSpace::from(vec![17, -2, 7, 1]);
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let yspace = AxisSpace::from(vec![5, -8, -6, -10]);
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let zspace = AxisSpace::from(vec![1, 8, 14, 4]);
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let total = lcm3(xspace.reapeats(), yspace.reapeats(), zspace.reapeats());
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println!("matching space found {} iterations ago", total);
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn day12example1() {
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let space = Space::from(vec![
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Object::from((-1, 0, 2)),
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Object::from((2, -10, -7)),
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Object::from((4, -8, 8)),
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Object::from((3, 5, -1)),
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]);
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assert!(space.status().eq(vec![
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(&Object::from((-1, 0, 2)), &Object::default()),
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(&Object::from((2, -10, -7)), &Object::from((0, 0, 0))),
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(&Object::from((4, -8, 8)), &Object::from((0, 0, 0))),
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(&Object::from((3, 5, -1)), &Object::from((0, 0, 0))),
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]));
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}
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#[test]
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fn day12part1() {
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let mut space = Space::from(vec![
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Object::from((17, 5, 1)),
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Object::from((-2, -8, 8)),
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Object::from((7, -6, 14)),
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Object::from((1, -10, 4)),
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]);
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(1..=1000).for_each(|_| {
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space.step();
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});
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let energy = space
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.status()
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.map(|(o, v)| {
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println!("{:?} {:?}", o, v);
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o.energy() * v.energy()
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})
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.fold(0, |mut acc, c| {
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acc += c;
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acc
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});
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assert_eq!(energy, 9876)
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}
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#[test]
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fn day12example2() {
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let space = Space::from(vec![
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Object::from((-1, 0, 2)),
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Object::from((2, -10, -7)),
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Object::from((4, -8, 8)),
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Object::from((3, 5, -1)),
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]);
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assert_eq!(space.reapeats(), 2772)
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}
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}
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