52 lines
1.3 KiB
Rust
52 lines
1.3 KiB
Rust
use crate::prelude::*;
|
|
|
|
pub fn solution() -> Solution {
|
|
Solution::new(Day::new(10, 2020), part_1, part_2)
|
|
.with_expected(2368, 1727094849536_i64)
|
|
}
|
|
|
|
fn parse_numbers(input: &str) -> (HashMap<usize, i32>, HashMap<i32, u32>) {
|
|
let mut numbers = input
|
|
.lines()
|
|
.map(|line| line.parse().unwrap())
|
|
.collect::<Vec<usize>>();
|
|
|
|
numbers.push(0);
|
|
numbers.sort_unstable();
|
|
numbers.push(numbers.last().unwrap() + 3);
|
|
|
|
let mut intervals = HashMap::new();
|
|
let mut streaks = HashMap::new();
|
|
let mut streak_length = 0;
|
|
for (index, a) in numbers.iter().enumerate() {
|
|
if let Some(b) = numbers.get(index + 1) {
|
|
let interval = b - a;
|
|
if interval == 1 {
|
|
streak_length += 1;
|
|
} else {
|
|
*streaks.entry(streak_length).or_insert(0) += 1;
|
|
streak_length = 0;
|
|
}
|
|
|
|
*intervals.entry(interval).or_insert(0) += 1;
|
|
}
|
|
}
|
|
|
|
(intervals, streaks)
|
|
}
|
|
|
|
fn part_1(input: &str) -> Result<String> {
|
|
let (intervals, _) = parse_numbers(input);
|
|
Ok((intervals.get(&1).unwrap() * intervals.get(&3).unwrap()).to_string())
|
|
}
|
|
|
|
fn part_2(input: &str) -> Result<String> {
|
|
let (_, streaks) = parse_numbers(input);
|
|
Ok(
|
|
(7_usize.pow(*streaks.get(&4).unwrap())
|
|
* 4_usize.pow(*streaks.get(&3).unwrap())
|
|
* 2_usize.pow(*streaks.get(&2).unwrap()))
|
|
.to_string(),
|
|
)
|
|
}
|