59 lines
1.4 KiB
Rust
59 lines
1.4 KiB
Rust
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#![feature(int_abs_diff)]
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#![feature(test)]
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extern crate test;
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use aoc2021::common::*;
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use itertools::{Itertools, MinMaxResult};
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const DAY: usize = 7;
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type Parsed = Vec<usize>;
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fn parse_input(raw: &str) -> Parsed {
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parse_nums_comma(raw)
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}
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fn min_max(parsed: &Vec<usize>) -> (usize, usize) {
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match parsed.iter().minmax() {
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MinMaxResult::MinMax(&min, &max) => (min, max),
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_ => unreachable!("List not long enough"),
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}
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}
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fn part1(parsed: &Parsed) -> usize {
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let (min, max) = min_max(parsed);
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(min..=max).map(|x| parsed.iter().map(|p| p.abs_diff(x)).sum()).min().unwrap()
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}
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fn sum_to(n: usize) -> usize {
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(1..=n).sum()
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}
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fn part2(parsed: &Parsed) -> usize {
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let (min, max) = min_max(parsed);
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(min..=max).map(|x| parsed.iter().map(|p| p.abs_diff(x)).map(sum_to).sum()).min().unwrap()
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}
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fn main() {
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let input = parse_input(&read_file(DAY));
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println!("Part 1: {}", part1(&input));
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println!("Part 2: {}", part2(&input));
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use aoc2021::*;
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const TEST_INPUT: &str = "16,1,2,0,4,2,7,1,2,14";
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test!(part1() == 37);
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test!(part2() == 168);
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bench!(part1() == 328318);
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bench!(part2() == 89791146);
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bench_input!(Vec::len => 1000);
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#[bench]
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fn bench_sum_to(b: &mut test::Bencher) {
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b.iter(|| assert_eq!(sum_to(test::black_box(1000000)), 500000500000))
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}
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}
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