Add messy day 8

bram/rust/Cargo.toml

@@ -5,4 +5,6 @@ edition = "2024"
 
 [dependencies]
 colored = "3.0.0"
+itertools = "0.14.0"
+petgraph = "0.8.3"
 regex = "1.12.2"

bram/rust/src/day_08/mod.rs

@@ -1,5 +1,129 @@
-// use crate::utils;
+use crate::utils;
+use itertools::Itertools;
+use petgraph::unionfind::UnionFind;
+use std::collections::{BinaryHeap, HashMap};
 
-pub fn answer(_text: String) -> (u32, u32) {
+const COORD_SPACE: usize = 1000;
-    ( 0, 0 )
+const MAX_PAIRS: usize = 1000;
+
+pub fn answer(text: String) -> (usize, u32) {
+    // Get coordinates
+    let coords: [Coord; COORD_SPACE] = text.trim()
+        .split_whitespace()
+        .filter_map(Coord::from)
+        .collect::<Vec<Coord>>()
+        .try_into()
+        .unwrap();
+
+    // Find all equivalence classes
+    let pairs = PairQueue::from(&coords);
+    let mut uf = UnionFind::new(COORD_SPACE);
+
+    for ( c1, c2 ) in pairs.pairs.iter().rev().map(|cp| (cp.c1, cp.c2)) {
+        // println!("Coord {c1} ({:?}) and coord {c2} ({:?}) are close together!", coords[c1], coords[c2]);
+        uf.union(c1, c2);
+    }
+    println!("{:?}", uf);
+
+    // Collect sizes of equivalence classes
+    let mut groups: HashMap<usize, usize> = HashMap::new();
+    for x in uf.into_labeling().iter() {
+        *groups.entry(*x).or_insert(0) += 1;
+    }
+    println!("{:?}", groups);
+
+    let mut equiv_class_sizes : Vec<isize> = groups
+        .values()
+        .map(|v| -1 * (*v as isize))
+        .collect();
+    equiv_class_sizes.sort_unstable();
+
+    println!("{:?}", equiv_class_sizes);
+
+    ( (equiv_class_sizes[0] * equiv_class_sizes[1] * equiv_class_sizes[2]).abs() as usize
+    // 87048 too high
+    , 0
+    )
+}
+
+#[derive(Debug)]
+struct Coord { x: u64, y: u64, z: u64, }
+impl Coord {
+    fn dist_euclid(&self, other: &Coord) -> i64 {
+        ( self.x.abs_diff(other.x).pow(2)
+        + self.y.abs_diff(other.y).pow(2)
+        + self.z.abs_diff(other.z).pow(2)
+        ) as i64
+    }
+
+    fn from(s: &str) -> Option<Coord> {
+        let ( x, yz ) = s.split_once(",")?;
+        let ( y, z ) = yz.split_once(",")?;
+
+        Some(Coord {
+            x: utils::str_to_u64(x)?,
+            y: utils::str_to_u64(y)?,
+            z: utils::str_to_u64(z)?,
+        })
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
+struct CoordPair {
+    distance: i64,
+    c1 : usize,
+    c2 : usize,
+}
+
+struct PairQueue {
+    max_distance: i64,
+    pairs: BinaryHeap<CoordPair>,
+}
+impl PairQueue {
+    fn from(coords: &[Coord; COORD_SPACE]) -> PairQueue {
+        let pairs = coords
+            .iter()
+            .enumerate()
+            .combinations(2);
+        let mut queue = PairQueue::new();
+
+        for pair in pairs {
+            let (i, c1) = pair[0];
+            let (j, c2) = pair[1];
+
+            queue.insert(
+                CoordPair { distance: c1.dist_euclid(c2), c1: i, c2: j }
+            );
+        }
+
+        queue
+    }
+
+    fn insert(&mut self, pair: CoordPair) {
+        // println!("At max: {} (size {}) | Distance = {} | Max distance = {} (too large: {})", self.pairs.len() >= MAX_PAIRS, self.pairs.len(), pair.distance, self.max_distance, pair.distance >= self.max_distance);
+        if self.pairs.len() >= MAX_PAIRS && pair.distance >= self.max_distance {
+            // println!("STOPPING!");
+            return;
+        }
+
+        self.max_distance = self.pairs
+            .peek()
+            .map(|cp| cp.distance)
+            .unwrap_or(pair.distance)
+            .max(pair.distance);
+        // println!("Going on! Self distance = {}, pair distance = {}", self.max_distance, pair.distance);
+
+        self.pairs.push(pair);
+        if self.pairs.len() > MAX_PAIRS {
+            self.pairs.pop();
+            // println!("Popping {:?}", self.pairs.pop());
+        }
+    }
+
+    fn new() -> PairQueue {
+        PairQueue {
+            max_distance: 0,
+            pairs: BinaryHeap::with_capacity(COORD_SPACE + 1)
+        }
+    }
 }

bram/rust/src/utils/mod.rs

@@ -28,6 +28,10 @@ pub fn str_to_i16(s : &str) -> Option<i16> {
     s.trim().to_string().parse::<i16>().ok()
 }
 
+pub fn str_to_i64(s : &str) -> Option<i64> {
+    s.trim().to_string().parse::<i64>().ok()
+}
+
 // pub fn str_to_i32(s : &str) -> Option<i32> {
 //     s.trim().to_string().parse::<i32>().ok()
 // }