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|
use std::fs;
use std::path::Path;
use regex::Regex;
use lazy_static::lazy_static;
#[derive(Debug,PartialEq)]
struct Segment(u32,u32,u32,u32);
impl Segment {
fn is_hor(&self) -> bool {
self.1 == self.3
}
fn is_ver(&self) -> bool {
self.0 == self.2
}
}
/* AOC21 Day 7: https://adventofcode.com/2021/day/7 */
fn main() {
let input = Path::new("resources").join("input.txt");
let content = fs::read_to_string(input).expect("Unable to read input file");
let (size, segments) = parse_input(&content);
let area = radar(&segments, size, false);
println!("Ex1: The result is: {}", area.iter().filter(|&&c| c > 1).count());
let area = radar(&segments, size, true);
println!("Ex2: The result is: {}", area.iter().filter(|&&c| c > 1).count());
}
fn radar(segments: &[Segment], size: u32, diagonals: bool) -> Vec<u32> {
let mut area = vec![0;(size+1).pow(2) as usize];
segments.iter().for_each(
|s| match s {
s if s.is_hor() => {
range(s.0, s.2).iter().for_each(|x| area[((size+1)*s.1 + x) as usize] += 1)
},
s if s.is_ver() => {
range(s.1, s.3).iter().for_each(|y| area[((size+1)*y + s.0) as usize] += 1)
},
s => {
if diagonals {
range(s.0,s.2).iter().zip(range(s.1,s.3)).for_each(|(x,y)| area[((size+1)*y + x) as usize] += 1)
}
}
}
);
area
}
fn parse_input(s: &str) -> (u32, Vec<Segment>) {
lazy_static! {
static ref RE: Regex = Regex::new(r"^(\d+),(\d+) -> (\d+),(\d+)$").unwrap();
}
let mut max = 0;
let segs = s.lines().map(|l| {
let caps = RE.captures(l).expect("Malformed input");
let x1 = caps.get(1).unwrap().as_str().parse().expect("Malformed input");
let y1 = caps.get(2).unwrap().as_str().parse().expect("Malformed input");
let x2 = caps.get(3).unwrap().as_str().parse().expect("Malformed input");
let y2 = caps.get(4).unwrap().as_str().parse().expect("Malformed input");
max = *[x1, x2, y1, y2, max].iter().max().unwrap();
Segment(x1, y1, x2, y2)
}).collect();
(max, segs)
}
fn range(from: u32, to: u32) -> Vec<u32> {
if from < to {
(from..=to).collect()
} else {
(to..=from).rev().collect()
}
}
#[cfg(test)]
mod tests {
use super::*;
const INPUT: &str = "0,9 -> 5,9
8,0 -> 0,8
9,4 -> 3,4
2,2 -> 2,1
7,0 -> 7,4
6,4 -> 2,0
0,9 -> 2,9
3,4 -> 1,4
0,0 -> 8,8
5,5 -> 8,2";
#[test]
fn input_parsing() {
let (size, segments) = parse_input(INPUT);
assert_eq!(9,size);
assert_eq!(vec![
Segment(0,9,5,9),
Segment(8,0,0,8),
Segment(9,4,3,4),
Segment(2,2,2,1),
Segment(7,0,7,4),
Segment(6,4,2,0),
Segment(0,9,2,9),
Segment(3,4,1,4),
Segment(0,0,8,8),
Segment(5,5,8,2),
],segments);
}
#[test]
fn examples() {
let (size, segments) = parse_input(INPUT);
assert_eq!(vec![
0,0,0,0,0,0,0,1,0,0,
0,0,1,0,0,0,0,1,0,0,
0,0,1,0,0,0,0,1,0,0,
0,0,0,0,0,0,0,1,0,0,
0,1,1,2,1,1,1,2,1,1,
0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,
2,2,2,1,1,1,0,0,0,0
], radar(&segments, size, false));
assert_eq!(vec![
1,0,1,0,0,0,0,1,1,0,
0,1,1,1,0,0,0,2,0,0,
0,0,2,0,1,0,1,1,1,0,
0,0,0,1,0,2,0,2,0,0,
0,1,1,2,3,1,3,2,1,1,
0,0,0,1,0,2,0,0,0,0,
0,0,1,0,0,0,1,0,0,0,
0,1,0,0,0,0,0,1,0,0,
1,0,0,0,0,0,0,0,1,0,
2,2,2,1,1,1,0,0,0,0
], radar(&segments, size, true))
}
}
|
