103 lines
2.7 KiB
Rust
103 lines
2.7 KiB
Rust
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extern crate regex;
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use regex::Regex;
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use std::collections::HashSet;
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use std::fs::File;
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use std::io::{BufRead, BufReader};
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use std::iter::Iterator;
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#[derive(Debug)]
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struct Point {
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x: i32,
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y: i32,
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x_velocity: i32,
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y_velocity: i32
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}
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fn bounding_box(points: &Vec<Point>) -> (i32, i32, i32, i32) {
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let mut min_x = std::i32::MAX;
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let mut min_y = std::i32::MAX;
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let mut max_x = std::i32::MIN;
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let mut max_y = std::i32::MIN;
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for p in points.iter() {
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if min_x > p.x { min_x = p.x };
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if min_y > p.y { min_y = p.y };
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if max_x < p.x { max_x = p.x };
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if max_y < p.y { max_y = p.y };
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}
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(min_x, min_y, max_x, max_y)
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}
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fn tick(points: &mut Vec<Point>) -> i32 {
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let mut seconds = 0;
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let mut old_height = std::i32::MAX;
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loop {
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let (_min_x, min_y, _max_x, max_y) = bounding_box(points);
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let new_height = max_y - min_y;
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if new_height > old_height {
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for p in points.iter_mut() {
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p.x -= p.x_velocity;
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p.y -= p.y_velocity;
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}
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seconds -= 1;
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break;
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}
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old_height = new_height;
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seconds += 1;
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for p in points.iter_mut() {
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p.x += p.x_velocity;
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p.y += p.y_velocity;
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}
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}
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let (min_x, min_y, max_x, max_y) = bounding_box(points);
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println!("final bounding box: ({}, {}) ({}, {})", min_x, min_y, max_x, max_y);
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let mut final_set = HashSet::with_capacity(points.len());
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for p in points.iter() {
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final_set.insert((p.x, p.y));
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}
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for j in min_y..=max_y {
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for i in min_x..=max_x {
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if final_set.contains(&(i, j)) {
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print!("#")
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} else {
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print!(".")
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};
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}
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println!("");
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}
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seconds
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}
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fn main() {
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let lines: Vec<String> = BufReader::new(File::open("input").unwrap())
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.lines()
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.map(|line| line.unwrap())
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.collect();
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let mut points: Vec<Point> = Vec::with_capacity(lines.len());
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let re = Regex::new(r"^position=<([-| ]\d+), ([-| ]\d+)> velocity=<([-| ]\d), ([-| ]\d)>$").unwrap();
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for line in lines.iter() {
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if re.is_match(line) {
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let cap = re.captures(line).unwrap();
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let x = cap[1].trim_start().parse::<i32>().unwrap();
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let y = cap[2].trim_start().parse::<i32>().unwrap();
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let x_velocity = cap[3].trim_start().parse::<i32>().unwrap();
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let y_velocity = cap[4].trim_start().parse::<i32>().unwrap();
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points.push(Point {
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x,
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y,
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x_velocity,
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y_velocity
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});
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}
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}
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let seconds = tick(&mut points);
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println!("time elapsed: {}", seconds);
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}
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