day12 task 2

Cargo.lock

@@ -13,9 +13,15 @@ name = "aoc_2019"
 version = "0.1.0"
 dependencies = [
  "itertools 0.8.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-integer 0.1.41 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 1.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "autocfg"
+version = "0.1.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "either"
 version = "1.5.3"
@@ -39,6 +45,23 @@ name = "memchr"
 version = "2.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "num-integer"
+version = "0.1.41"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "autocfg 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-traits 0.2.10 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "num-traits"
+version = "0.2.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "autocfg 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "regex"
 version = "1.3.1"
@@ -65,10 +88,13 @@ dependencies = [
 
 [metadata]
 "checksum aho-corasick 0.7.6 (registry+https://github.com/rust-lang/crates.io-index)" = "58fb5e95d83b38284460a5fda7d6470aa0b8844d283a0b614b8535e880800d2d"
+"checksum autocfg 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)" = "1d49d90015b3c36167a20fe2810c5cd875ad504b39cff3d4eae7977e6b7c1cb2"
 "checksum either 1.5.3 (registry+https://github.com/rust-lang/crates.io-index)" = "bb1f6b1ce1c140482ea30ddd3335fc0024ac7ee112895426e0a629a6c20adfe3"
 "checksum itertools 0.8.2 (registry+https://github.com/rust-lang/crates.io-index)" = "f56a2d0bc861f9165be4eb3442afd3c236d8a98afd426f65d92324ae1091a484"
 "checksum lazy_static 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
 "checksum memchr 2.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "88579771288728879b57485cc7d6b07d648c9f0141eb955f8ab7f9d45394468e"
+"checksum num-integer 0.1.41 (registry+https://github.com/rust-lang/crates.io-index)" = "b85e541ef8255f6cf42bbfe4ef361305c6c135d10919ecc26126c4e5ae94bc09"
+"checksum num-traits 0.2.10 (registry+https://github.com/rust-lang/crates.io-index)" = "d4c81ffc11c212fa327657cb19dd85eb7419e163b5b076bede2bdb5c974c07e4"
 "checksum regex 1.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "dc220bd33bdce8f093101afe22a037b8eb0e5af33592e6a9caafff0d4cb81cbd"
 "checksum regex-syntax 0.6.12 (registry+https://github.com/rust-lang/crates.io-index)" = "11a7e20d1cce64ef2fed88b66d347f88bd9babb82845b2b858f3edbf59a4f716"
 "checksum thread_local 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)" = "c6b53e329000edc2b34dbe8545fd20e55a333362d0a321909685a19bd28c3f1b"

Cargo.toml

@@ -9,3 +9,4 @@ edition = "2018"
 [dependencies]
 itertools = "0.8.2"
 regex = "1.3.1"
+num-integer = "0.1"

src/main.rs

@@ -1,5 +1,5 @@
 mod tasks;
 
 fn main() {
-    tasks::day14::run();
+    tasks::day12::run();
 }

src/tasks/day12.rs

@@ -1,3 +1,4 @@
+use num_integer::Integer;
 use regex::Regex;
 
 #[allow(dead_code)]
@@ -14,10 +15,6 @@ pub fn run() {
             Point { x, y, z }
         })
         .collect();
-    task1(input.clone());
-}
-
-fn task1(input: Vec<Point>) {
     let moons: Vec<_> = input
         .into_iter()
         .map(|pos| Moon {
@@ -25,42 +22,84 @@ fn task1(input: Vec<Point>) {
             vel: Point::new(0, 0, 0),
         })
         .collect();
-    let finals = (0..1000).fold(moons, |moons, _run| {
+    task1(moons.clone());
-        let gravities: Vec<Point> = moons
+    task2(moons.clone());
-            .iter()
+}
-            .map(|base| {
+
-                moons.iter().fold(Point::new(0, 0, 0), |grav, other_moon| {
+fn task1(moons: Vec<Moon>) {
-                    grav.add(base.pos.gravity(other_moon.pos))
+    let finals = (0..1000).fold(moons, |moons, _run| step(moons));
-                })
-            })
-            .collect();
-        let moons = moons
-            .into_iter()
-            .zip(gravities.into_iter())
-            .map(|(mut moon, grav)| {
-                moon.vel = moon.vel.add(grav);
-                moon.pos = moon.pos.add(moon.vel);
-                moon
-            })
-            .collect();
-        //println!("{}: {:?}", run, moons);
-        moons
-    });
     let energy: i32 = finals
         .iter()
         .map(|moon| moon.pos.energy() * moon.vel.energy())
         .sum();
     println!("Task 1: sum of energy is {}", energy);
-    //392 too low
 }
 
-#[derive(Debug)]
+fn task2(moons: Vec<Moon>) {
+    let xstart: Vec<_> = moons.iter().map(|it| [it.pos.x, it.vel.x]).collect();
+    let ystart: Vec<_> = moons.iter().map(|it| [it.pos.y, it.vel.y]).collect();
+    let zstart: Vec<_> = moons.iter().map(|it| [it.pos.z, it.vel.z]).collect();
+    let result = (1 as usize..)
+        .scan((None, None, None, moons), |(dx, dy, dz, moons), run| {
+            let mut new_moons = step(moons.clone());
+            moons.clear();
+            moons.append(&mut new_moons);
+
+            let xv: Vec<_> = moons.iter().map(|it| [it.pos.x, it.vel.x]).collect();
+            let yv: Vec<_> = moons.iter().map(|it| [it.pos.y, it.vel.y]).collect();
+            let zv: Vec<_> = moons.iter().map(|it| [it.pos.z, it.vel.z]).collect();
+            if *dx == None && xv == xstart {
+                *dx = Some(run);
+            }
+            if *dy == None && yv == ystart {
+                *dy = Some(run);
+            }
+            if *dz == None && zv == zstart {
+                *dz = Some(run);
+            }
+            if dx.is_some() && dy.is_some() && dz.is_some() {
+                Some(Some((dx.unwrap(), dy.unwrap(), dz.unwrap())))
+            } else {
+                Some(None)
+            }
+        })
+        .find(|bla| bla.is_some());
+    if let Some(Some((x, y, z))) = result {
+        println!(
+            "Task 2: {:?} until a visited state is reached again",
+            x.lcm(&y.lcm(&z))
+        );
+    }
+}
+
+fn step(moons: Vec<Moon>) -> Vec<Moon> {
+    let gravities: Vec<Point> = moons
+        .iter()
+        .map(|base| {
+            moons.iter().fold(Point::new(0, 0, 0), |grav, other_moon| {
+                grav.add(base.pos.gravity(other_moon.pos))
+            })
+        })
+        .collect();
+    let moons = moons
+        .into_iter()
+        .zip(gravities.into_iter())
+        .map(|(mut moon, grav)| {
+            moon.vel = moon.vel.add(grav);
+            moon.pos = moon.pos.add(moon.vel);
+            moon
+        })
+        .collect();
+    moons
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash, Ord, PartialOrd)]
 struct Moon {
     pos: Point,
     vel: Point,
 }
 
-#[derive(Clone, Copy, Debug)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, Ord, PartialOrd)]
 struct Point {
     x: i32,
     y: i32,