day8: non working progress

src/day8.rs

@@ -0,0 +1,173 @@
+use std::{
+    collections::{HashMap, HashSet},
+    f64,
+    fmt::{Display, Write},
+    iter::repeat_n,
+};
+
+use aoc_runner_derive::{aoc, aoc_generator};
+use cached::proc_macro::cached;
+use itertools::Itertools;
+
+#[derive(Eq, PartialEq, Clone, Debug, Hash)]
+struct Junction {
+    pos: (i64, i64, i64),
+}
+
+fn distance(a: &Junction, b: &Junction) -> f64 {
+    if a.pos == b.pos {
+        f64::MAX // ugh
+    } else {
+        (((a.pos.0 - b.pos.0).pow(2) + (a.pos.1 - b.pos.1).pow(2) + (a.pos.2 - b.pos.2).pow(2))
+            as f64)
+            .sqrt()
+    }
+}
+
+impl Junction {
+    fn distance(&self, other: &Junction) -> f64 {
+        distance(self, other)
+    }
+}
+
+impl Display for Junction {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_fmt(format_args!(
+            "({},{},{})",
+            self.pos.0, self.pos.1, self.pos.2
+        ))
+    }
+}
+
+impl From<&str> for Junction {
+    fn from(value: &str) -> Self {
+        Self {
+            pos: value
+                .split(',')
+                .map(|v| v.parse().unwrap())
+                .collect_tuple()
+                .unwrap(),
+        }
+    }
+}
+
+#[derive(Clone)]
+struct Circuits {
+    junctions: Vec<Junction>,
+    circuits: Vec<Vec<usize>>,
+    checked: HashSet<(usize, usize)>,
+}
+
+impl Circuits {
+    fn find_circuit(&self, junction: usize) -> Option<usize> {
+        self.circuits
+            .iter()
+            .enumerate()
+            .find(|(_i, c)| c.contains(&junction))
+            .map(|(i, _c)| i)
+    }
+    fn merge_circuits(&mut self, a: usize, b: usize) {
+        if a == b {
+            return;
+        }
+        let mut items = Vec::new();
+        std::mem::swap(&mut items, &mut self.circuits[b]);
+        self.circuits[a].append(&mut items);
+        self.circuits.remove(b);
+    }
+
+    fn connect(&mut self, a: usize, b: usize) {
+        let a_circuit = self.find_circuit(a);
+        let b_circuit = self.find_circuit(b);
+        self.checked.insert((a, b));
+
+        match (a_circuit, b_circuit) {
+            (None, None) => self.circuits.push(vec![a, b]), // both are unconnected
+            (Some(a_circuit), Some(b_circuit)) => {
+                self.merge_circuits(a_circuit, b_circuit); // both are already in circuits, merge them
+            }
+            (Some(a_circuit), None) => self.circuits[a_circuit].push(b), // one is in a circuit, so add the other to the existing circuit
+            (None, Some(b_circuit)) => self.circuits[b_circuit].push(a),
+        };
+    }
+}
+
+#[aoc_generator(day8)]
+fn parse(input: &str) -> Circuits {
+    let junctions = input.lines().map(|l| l.into()).collect_vec();
+
+    Circuits {
+        junctions,
+        circuits: Vec::new(),
+        checked: HashSet::new(),
+    }
+}
+
+#[aoc(day8, part1)]
+fn part1(input: &Circuits) -> u64 {
+    let mut circuits = input.clone();
+    for (a, b, d) in circuits
+        .junctions
+        .iter()
+        .enumerate()
+        .combinations(2)
+        .map(|p| (p[0].0, p[1].0, p[0].1.distance(p[1].1)))
+        .sorted_by(|a, b| a.2.partial_cmp(&b.2).unwrap())
+        .take(1000)
+    {
+        println!(
+            "connecting {} <-> {} = {d}",
+            circuits.junctions[a], circuits.junctions[b]
+        );
+        circuits.connect(a, b)
+    }
+    println!("{:?}", circuits.circuits);
+    circuits
+        .circuits
+        .iter()
+        .take(3)
+        .map(|c| c.len())
+        .reduce(|a, b| a * b)
+        .unwrap() as u64
+}
+
+#[aoc(day8, part2)]
+fn part2(input: &Circuits) -> u64 {
+    0
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const EXAMPLE: &str = "162,817,812
+57,618,57
+906,360,560
+592,479,940
+352,342,300
+466,668,158
+542,29,236
+431,825,988
+739,650,466
+52,470,668
+216,146,977
+819,987,18
+117,168,530
+805,96,715
+346,949,466
+970,615,88
+941,993,340
+862,61,35
+984,92,344
+425,690,689";
+
+    #[test]
+    fn part1_example() {
+        assert_eq!(part1(&parse(EXAMPLE)), 40);
+    }
+
+    #[test]
+    fn part2_example() {
+        assert_eq!(part2(&parse(EXAMPLE)), 0);
+    }
+}

src/lib.rs

@@ -5,6 +5,7 @@ mod day4;
 mod day5;
 mod day6;
 mod day7;
+mod day8;
 
 use aoc_runner_derive::aoc_lib;