84 lines
2.6 KiB
Rust
84 lines
2.6 KiB
Rust
use std::env;
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use std::fs::File;
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use std::io::{BufReader, BufRead};
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use std::cmp::{min, max};
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use std::collections::HashSet;
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fn parse_num(s: &[u8]) -> (i64, usize) {
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let mut num: i64 = 0;
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let negative = s[0] == '-' as u8;
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let start = if negative {1} else {0};
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let mut len = if negative {1} else {0};
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for i in start..s.len() {
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if s[i].is_ascii_digit() {
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num = num*10 + (s[i] as i64 - '0' as i64);
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len += 1;
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} else {
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break;
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}
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}
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(if negative {-num} else {num}, len)
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}
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fn combine(ranges: &mut Vec<(i64, i64)>, l: i64, r: i64) {
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for (l0, r0) in ranges.iter_mut() {
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if *l0 <= r && l <= *r0 {
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*l0 = min(*l0, l);
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*r0 = max(*r0, r);
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return;
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}
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}
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if ranges.len() > 0 {
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let (_, last_r) = ranges.last_mut().unwrap();
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if l == *last_r + 1 {
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*last_r = r;
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return;
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}
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}
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ranges.push((l, r));
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}
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fn main() {
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let file = File::open(&env::args().nth(1).expect("input")).expect("io err");
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let lines = BufReader::new(file).lines();
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let mut sensors: Vec<(i64, i64, u64)> = Vec::new();
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let mut beacons: HashSet<(i64, i64)> = HashSet::new();
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for line in lines.flatten() {
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let l_bytes = line.as_bytes();
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let (sx, e1) = parse_num(&l_bytes[12..]);
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let (sy, e2) = parse_num(&l_bytes[12 + e1 + 4..]);
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let (bx, e3) = parse_num(&l_bytes[12 + e1 + 4 + e2 + 25..]);
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let (by, _) = parse_num(&l_bytes[12 + e1 + 4 + e2 + 25 + e3 + 4..]);
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sensors.push((sx, sy, ((bx - sx).abs() + (by - sy).abs()) as u64));
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beacons.insert((bx, by));
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}
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sensors.sort_by_key(|(x, _, _)| *x);
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println!("{:?}", sensors);
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println!("{:?}", beacons);
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let max_y = &env::args().nth(2).expect("max y").parse::<i64>().unwrap();
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for target_y in 0..=*max_y {
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let mut line_coverages: Vec<(i64, i64)> = Vec::new();
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for (sx, sy, range) in &sensors {
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let clip = (*range as i64) - (sy - target_y).abs();
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if clip < 0 {
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continue;
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}
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let startx = sx - clip;
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let endx = sx + clip;
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line_coverages.push((startx, endx));
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}
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line_coverages.sort_by_key(|(x, _)| *x);
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let mut coverage: Vec<(i64, i64)> = Vec::new();
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for (startx, endx) in line_coverages {
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combine(&mut coverage, startx, endx);
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}
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if coverage.len() > 1 {
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let score = 4000000 * (coverage[0].1 + 1) + target_y;
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println!("{:?} --> {:?}", coverage, score);
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break;
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}
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}
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}
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