Advent of Code solutions
Day 9 🫩
+88
-5
+72
-5
years/2025/src/day_9.rs
+72
-5
years/2025/src/day_9.rs
···
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use advent_core::{day_stuff, ex_for_day, Day};
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use utils::pos::Position;
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pub struct Day9;
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impl Day for Day9 {
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day_stuff!(9, "", "");
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day_stuff!(9, "50", "24", Vec<Position>);
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fn part_1(input: Self::Input) -> Option<String> {
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let ans = input
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.iter()
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.enumerate()
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.flat_map(|(i, a)| {
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input.iter().skip(i + 1).map(|b| {
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let p = (*b - *a).abs();
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(p.x + 1) * (p.y + 1)
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})
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})
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.max()
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.unwrap();
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Some(ans.to_string())
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}
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fn part_2(mut input: Self::Input) -> Option<String> {
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let mut max = 0;
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input.push(*input.first().unwrap());
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let lines = input.windows(2).map(|w| (w[0], w[1])).collect::<Vec<_>>();
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for (i, a) in input.iter().enumerate() {
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// println!("Start {} ({}/{})", *a, i + 1, input.len());
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for b in input.iter().skip(i + 1) {
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let p = (*b - *a).abs();
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let area = (p.x + 1) * (p.y + 1);
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if area > max {
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let check = lines.iter().any(|&l| {
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let (cons, b1, b2, c1, c2, r1, r2) = if l.0.x == l.1.x {
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(l.0.x, a.x, b.x, l.0.y, l.1.y, a.y, b.y)
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} else {
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(l.0.y, a.y, b.y, l.0.x, l.1.x, a.x, b.x)
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};
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let (lower_cons, upper_cons) = (b1.min(b2), b1.max(b2));
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let (line_range_lower, line_range_upper) = (c1.min(c2), c1.max(c2));
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let (rect_range_lower, rect_range_upper) = (r1.min(r2), r1.max(r2));
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let cons_in_range = cons > lower_cons && cons < upper_cons;
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let ranges_overlap = if line_range_lower < rect_range_lower {
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line_range_upper > rect_range_lower
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} else {
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rect_range_upper > line_range_lower
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};
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cons_in_range && ranges_overlap
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});
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fn part_1(_input: Self::Input) -> Option<String> {
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None
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if !check {
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max = area;
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}
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}
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}
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}
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Some(max.to_string())
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}
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fn part_2(_input: Self::Input) -> Option<String> {
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None
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fn parse_input(input: &str) -> Self::Input {
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input
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.lines()
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.map(|l| {
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let (x, y) = l.split_once(',').unwrap();
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Position {
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x: x.parse().unwrap(),
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y: y.parse().unwrap(),
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}
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})
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.collect()
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}
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}
+8
years/2025/src/examples/day_9/1.txt
+8
years/2025/src/examples/day_9/1.txt