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-rw-r--r--2018/src/day10.rs34
1 files changed, 29 insertions, 5 deletions
diff --git a/2018/src/day10.rs b/2018/src/day10.rs
index 28da8de..99be244 100644
--- a/2018/src/day10.rs
+++ b/2018/src/day10.rs
@@ -1,5 +1,6 @@
use std::io;
use std::io::BufRead;
+use std::cmp::max;
use std::collections::HashSet;
fn parse_pt(l: &str) -> ((i32, i32), (i32, i32)) {
@@ -19,6 +20,10 @@ fn parse_pt(l: &str) -> ((i32, i32), (i32, i32)) {
(s3.trim().parse().unwrap(), s4.trim().parse().unwrap()))
}
+fn dist((x, y): (i32, i32), (u, v): (i32, i32)) -> i32 {
+ return ((u - x) as f32 * (u - x) as f32 + (v - y) as f32 * (v - y) as f32).sqrt() as i32;
+}
+
pub fn main<T: BufRead>(reader: T) -> io::Result<(String, String)> {
let dots: Vec<((i32, i32), (i32, i32))> =
reader.lines().map(|l| l.unwrap())
@@ -28,15 +33,26 @@ pub fn main<T: BufRead>(reader: T) -> io::Result<(String, String)> {
let mut pts: Vec<_> = dots.iter().map(|&(xy, _)| xy).collect();
let vels: Vec<_> = dots.iter().map(|&(_, v)| v).collect();
+ let maxvel = vels.iter().map(|&xy| dist(xy, (0, 0)) + 1).max().unwrap();
+
let mut maxscore = -1;
- let mut maxat = (-1, vec![], HashSet::new());
- for iter in 0..20000 {
+ let mut maxat;
+ let mut iter = 0;
+ loop {
let mut has_dot: HashSet<(i32, i32)> = HashSet::new();
+
+ let mut avg = (0, 0);
let mut score = 0;
for &xy in &pts {
if has_dot.contains(&xy) { score += 1; }
- has_dot.insert(xy);
+ else { has_dot.insert(xy); }
+ avg.0 += xy.0;
+ avg.1 += xy.1;
}
+ avg.0 /= dots.len() as i32;
+ avg.1 /= dots.len() as i32;
+
+ let maxdist = pts.iter().map(|&xy| dist(xy, avg)).max().unwrap();
if score > maxscore {
maxscore = score;
@@ -46,10 +62,18 @@ pub fn main<T: BufRead>(reader: T) -> io::Result<(String, String)> {
}
}
+ let multiplier =
+ if maxdist > maxvel && maxdist > 100 { max(1, (maxdist - 100) / maxvel) }
+ else { 1 };
+
+ // println!("iter={} multiplier={} maxdist={} maxvel={}", iter, multiplier, maxdist, maxvel);
+
for i in 0..dots.len() {
- pts[i].0 += vels[i].0;
- pts[i].1 += vels[i].1;
+ pts[i].0 += multiplier * vels[i].0;
+ pts[i].1 += multiplier * vels[i].1;
}
+
+ iter += multiplier;
}
let mut part1 = String::new();