garnet/rust/puzzles/day2.rs
2025-12-10 10:51:30 +00:00

65 lines
1.6 KiB
Rust

use crate::puzzle::Puzzle;
pub const PUZZLE: Puzzle<Vec<(usize, usize)>, usize, 2> = Puzzle {
number: 2,
parser: |input| {
input
.strip_suffix("\n")
.unwrap()
.split(',')
.map(|range| {
match range
.split('-')
.map(|n| n.parse().unwrap())
.collect::<Vec<usize>>()[..]
{
[a, b] => (a, b),
_ => panic!(),
}
})
.collect()
},
parts: [
|input| {
input
.into_iter()
.flat_map(|(l, u)| {
(*l..(u + 1)).flat_map(|n| if is_repetition_2(n) { Some(n) } else { None })
})
.sum()
},
|input| {
input
.into_iter()
.flat_map(|(l, u)| {
(*l..(u + 1)).flat_map(|n| if is_repetition_n(n) { Some(n) } else { None })
})
.sum()
},
],
};
fn is_repetition_2(n: usize) -> bool {
let n = n.to_string();
let l = n.len();
let d = l / 2;
let r = l % 2;
if r == 0 { equal_chunks(&n, d) } else { false }
}
fn is_repetition_n(n: usize) -> bool {
let n = n.to_string();
let l = n.len();
let d = l / 2;
(1..(d + 1)).any(|i| equal_chunks(&n, i))
}
fn equal_chunks(n: &String, i: usize) -> bool {
let chars = n.chars().collect::<Vec<char>>();
let mut chunks = (chars[..]).chunks(i);
match chunks.next() {
None => true,
Some(x) => chunks.all(|y| y == x),
}
}