107 lines
3.0 KiB
Rust
107 lines
3.0 KiB
Rust
#![warn(clippy::all, clippy::pedantic)]
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use std::collections::{HashMap, VecDeque};
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use glam::IVec2;
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use pathfinding::prelude::dijkstra;
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/// day 17 part 1 of aoc 2023
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///
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/// # Arguments
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/// - input the input for today's puzzle
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///
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/// # Panics
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/// panics whne it cannot parse the input OR when ever the number of game numbers is greater than
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#[must_use]
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pub fn part1(input: &str) -> String {
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let (maxes, grid) = parse_input(input);
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let result = dijkstra(
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&(IVec2::splat(0), VecDeque::from([IVec2::splat(0)])),
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|(pos, lasts)| {
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[
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IVec2::new(0, 1),
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IVec2::new(0, -1),
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IVec2::new(1, 0),
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IVec2::new(-1, 0),
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]
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.into_iter()
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.filter_map(|x| {
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let next = x + *pos;
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if !((0..maxes.x).contains(&next.x) && (0..maxes.y).contains(&next.y)) {
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return None;
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}
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if lasts.len() > 1 && lasts[1] == next {
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return None;
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}
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let mut next_lasts = lasts.clone();
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next_lasts.push_front(next);
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if next_lasts.len() >= 5 {
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let dir = next_lasts[1] - next_lasts[0];
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let a = next_lasts[2] - next_lasts[1];
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let b = next_lasts[3] - next_lasts[2];
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let c = next_lasts[4] - next_lasts[3];
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if [a, b, c].into_iter().all(|x| x == dir) {
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None
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} else {
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next_lasts.pop_back();
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Some((next, next_lasts))
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}
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} else {
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Some((next, next_lasts))
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}
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})
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.map(|pos| (pos.clone(), *grid.get(&pos.0).unwrap()))
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.collect::<Vec<((IVec2, VecDeque<IVec2>), u32)>>()
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},
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|win| win.0 == maxes - 1,
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)
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.expect("a path should be found");
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result.1.to_string()
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}
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fn parse_input(input: &str) -> (IVec2, HashMap<IVec2, u32>) {
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let grid = input
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.lines()
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.enumerate()
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.flat_map(|(row, line)| {
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line.chars().enumerate().map(move |(col, c)| {
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(
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IVec2::new(col.try_into().unwrap(), row.try_into().unwrap()),
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c.to_digit(10).unwrap(),
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)
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})
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})
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.collect();
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let max_row = i32::try_from(input.lines().count()).unwrap();
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let max_col = i32::try_from(input.lines().next().unwrap().len()).unwrap();
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(IVec2::new(max_col, max_row), grid)
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}
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#[cfg(test)]
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mod test {
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use super::*;
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const INPUT: &str = "2413432311323
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3215453535623
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3255245654254
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3446585845452
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4546657867536
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1438598798454
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4457876987766
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3637877979653
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4654967986887
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4564679986453
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1224686865563
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2546548887735
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4322674655533";
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#[test]
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fn part1_works() {
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let result = part1(INPUT);
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assert_eq!(result, "102".to_string());
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}
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}
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