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use std::{
collections::{HashMap, HashSet},
io,
};
fn main() -> io::Result<()> {
let mut antennae: HashMap<char, Vec<(i32, i32)>> = HashMap::new();
let grid = io::stdin()
.lines()
.flatten()
.map(|s| s.chars().collect())
.collect::<Vec<Vec<char>>>();
let max = grid.first().unwrap().len() as i32;
let may = grid.len() as i32;
grid.iter()
.enumerate()
.flat_map(|(y, row)| {
row.iter()
.enumerate()
.filter(|(_, &c)| c != '.')
.map(move |(x, &c)| (c, (x as i32, y as i32)))
})
.for_each(|(c, p)| antennae.entry(c).or_default().push(p));
let mut silver = HashSet::new();
let mut gold = HashSet::new();
for ps in antennae.values() {
for (n, &p) in ps.iter().enumerate() {
for &t in &ps[n+1..] {
antinodes(p, t, (max, may), false).for_each(|n| {
silver.insert(n);
});
antinodes(p, t, (max, may), true).for_each(|n| {
gold.insert(n);
});
}
}
}
let silver = silver.len();
let gold = gold.len();
println!("silver: {silver}");
println!("gold: {gold}");
return Ok(());
}
fn antinodes(
a: (i32, i32),
b: (i32, i32),
max: (i32, i32),
gold: bool,
) -> impl Iterator<Item = (i32, i32)> {
let dx = b.0 - a.0;
let dy = b.1 - a.1;
let in_range = move |(x, y)| (0..max.0).contains(&x) && (0..max.1).contains(&y);
if !gold {
vec![(a.0 - dx, a.1 - dy), (b.0 + dx, b.1 + dy)]
} else {
(0..)
.map(|n| (a.0 - n * dx, a.1 - n * dy))
.take_while(move |&p| in_range(p))
.chain(
(0..)
.map(|n| (b.0 + n * dx, b.1 + n * dy))
.take_while(move |&p| in_range(p)),
)
.collect()
}
.into_iter()
.filter(move |&p| in_range(p))
}
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