Advent of Code solutions
Day 8
+152
-5
+110
-5
years/2025/src/day_8.rs
+110
-5
years/2025/src/day_8.rs
···
1
+
use std::{collections::HashMap, ops::Sub};
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2
2
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use advent_core::{Day, day_stuff, ex_for_day};
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4
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pub struct Day8;
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7
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#[derive(Debug, Clone, Copy, Eq, Hash, PartialEq)]
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pub struct Pos(isize, isize, isize);
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impl Sub for Pos {
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type Output = isize;
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fn sub(self, rhs: Self) -> Self::Output {
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(self.0 - rhs.0).pow(2) + (self.1 - rhs.1).pow(2) + (self.2 - rhs.2).pow(2)
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}
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}
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impl Day for Day8 {
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day_stuff!(8, "40", "25272", (usize, Vec<Pos>));
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8
-
day_stuff!(8, "", "");
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fn part_1((amnt, input): Self::Input) -> Option<String> {
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let mut circuits = input
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.iter()
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.enumerate()
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.map(|(i, &p)| (p, i))
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.collect::<HashMap<Pos, usize>>();
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+
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let mut distances = input
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.iter()
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.enumerate()
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.flat_map(|(i, p)| input.iter().skip(i + 1).map(|&p2| (*p, p2, *p - p2)))
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.collect::<Vec<_>>();
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distances.sort_by_key(|(_, _, x)| *x);
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for (p1, p2, _dist) in distances.into_iter().take(amnt) {
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let target_circ = circuits.get(&p1).copied().unwrap();
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let replace_circ = circuits.get(&p2).copied().unwrap();
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if target_circ == replace_circ {
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continue;
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}
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for (_p, v) in circuits.iter_mut().filter(|(_, v)| **v == replace_circ) {
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*v = target_circ;
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}
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}
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let mut counts = circuits
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.into_iter()
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.fold(HashMap::new(), |mut acc, (_, c)| {
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*(acc.entry(c).or_insert(0)) += 1;
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acc
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})
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.into_iter()
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.map(|(_, count)| count)
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.collect::<Vec<_>>();
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counts.sort_by(|a, b| a.cmp(b).reverse());
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Some(
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counts
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.into_iter()
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.take(3)
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.fold(1, |acc, x| acc * x)
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.to_string(),
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)
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}
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fn part_2((_amnt, input): Self::Input) -> Option<String> {
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let mut circuits = input
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.iter()
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.enumerate()
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.map(|(i, &p)| (p, i))
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.collect::<HashMap<Pos, usize>>();
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+
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let mut distances = input
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.iter()
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.enumerate()
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.flat_map(|(i, p)| input.iter().skip(i + 1).map(|&p2| (*p, p2, *p - p2)))
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.collect::<Vec<_>>();
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distances.sort_by_key(|(_, _, x)| *x);
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let mut last_2: Option<(Pos, Pos)> = None;
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for (p1, p2, _dist) in distances.into_iter() {
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let target_circ = circuits.get(&p1).copied().unwrap();
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let replace_circ = circuits.get(&p2).copied().unwrap();
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if target_circ == replace_circ {
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continue;
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}
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last_2 = Some((p1, p2));
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-
fn part_1(_input: Self::Input) -> Option<String> {
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None
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for (_p, v) in circuits.iter_mut().filter(|(_, v)| **v == replace_circ) {
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*v = target_circ;
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}
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}
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let (a, b) = last_2.unwrap();
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Some((a.0 * b.0).to_string())
12
105
}
13
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-
fn part_2(_input: Self::Input) -> Option<String> {
15
-
None
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fn parse_input(input: &str) -> Self::Input {
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let mut lines = input.lines();
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let amnt = lines.next().unwrap().parse::<usize>().unwrap();
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let poses = lines
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.map(|l| {
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let (x, r) = l.split_once(',').unwrap();
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let (y, z) = r.split_once(',').unwrap();
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Pos(x.parse().unwrap(), y.parse().unwrap(), z.parse().unwrap())
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})
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.collect();
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(amnt, poses)
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}
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}
+21
years/2025/src/examples/day_8/1.txt
+21
years/2025/src/examples/day_8/1.txt
···
1
+
10
2
+
162,817,812
3
+
57,618,57
4
+
906,360,560
5
+
592,479,940
6
+
352,342,300
7
+
466,668,158
8
+
542,29,236
9
+
431,825,988
10
+
739,650,466
11
+
52,470,668
12
+
216,146,977
13
+
819,987,18
14
+
117,168,530
15
+
805,96,715
16
+
346,949,466
17
+
970,615,88
18
+
941,993,340
19
+
862,61,35
20
+
984,92,344
21
+
425,690,689
+21
years/2025/src/examples/day_8/2.txt
+21
years/2025/src/examples/day_8/2.txt
···
1
+
10
2
+
162,817,812
3
+
57,618,57
4
+
906,360,560
5
+
592,479,940
6
+
352,342,300
7
+
466,668,158
8
+
542,29,236
9
+
431,825,988
10
+
739,650,466
11
+
52,470,668
12
+
216,146,977
13
+
819,987,18
14
+
117,168,530
15
+
805,96,715
16
+
346,949,466
17
+
970,615,88
18
+
941,993,340
19
+
862,61,35
20
+
984,92,344
21
+
425,690,689