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Simplify day 7

This commit is contained in:
kageru 2021-12-07 14:06:09 +01:00
parent 413339cdb8
commit 744aa2fc72
1 changed files with 6 additions and 22 deletions
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28
2021/src/bin/day07.rs
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@ -2,7 +2,6 @@
#![feature(test)]
extern crate test;
use aoc2021::common::*;
use itertools::{Itertools, MinMaxResult};
const DAY: usize = 7;
type Parsed = Vec<usize>;
@ -11,25 +10,16 @@ fn parse_input(raw: &str) -> Parsed {
parse_nums_comma(raw)
}
fn min_max(parsed: &Vec<usize>) -> (usize, usize) {
match parsed.iter().minmax() {
MinMaxResult::MinMax(&min, &max) => (min, max),
_ => unreachable!("List not long enough"),
}
}
fn part1(parsed: &Parsed) -> usize {
let (min, max) = min_max(parsed);
(min..=max).map(|x| parsed.iter().map(|p| p.abs_diff(x)).sum()).min().unwrap()
}
fn sum_to(n: usize) -> usize {
(1..=n).sum()
let mut nums = parsed.to_owned();
nums.sort();
let median = nums[nums.len() / 2];
parsed.iter().map(|p| p.abs_diff(median)).sum()
}
fn part2(parsed: &Parsed) -> usize {
let (min, max) = min_max(parsed);
(min..=max).map(|x| parsed.iter().map(|p| p.abs_diff(x)).map(sum_to).sum()).min().unwrap()
let avg = parsed.iter().sum::<usize>() / parsed.len();
parsed.iter().map(|p| p.abs_diff(avg)).map(|n| (0..=n).sum::<usize>()).sum()
}
fn main() {
@ -46,13 +36,7 @@ mod tests {
const TEST_INPUT: &str = "16,1,2,0,4,2,7,1,2,14";
test!(part1() == 37);
test!(part2() == 168);
bench!(part1() == 328318);
bench!(part2() == 89791146);
bench_input!(Vec::len => 1000);
#[bench]
fn bench_sum_to(b: &mut test::Bencher) {
b.iter(|| assert_eq!(sum_to(test::black_box(1000000)), 500000500000))
}
}