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use advent_of_code::prelude::*;
pub fn parse(fh: File) -> Result<Vec<usize>> {
Ok(parse::split(fh, b',').collect())
}
pub fn part1(crabs: Vec<usize>) -> Result<usize> {
Ok((0..=crabs.iter().copied().max().unwrap())
.map(|start| {
crabs.iter().copied().map(|crab| crab.abs_diff(start)).sum()
})
.min()
.unwrap())
}
pub fn part2(crabs: Vec<usize>) -> Result<usize> {
Ok((0..=crabs.iter().copied().max().unwrap())
.map(|start| {
crabs
.iter()
.copied()
.map(|crab| {
let diff = crab.abs_diff(start);
diff * (diff + 1) / 2
})
.sum()
})
.min()
.unwrap())
}
#[test]
fn test() {
assert_eq!(
part1(parse(parse::data(2021, 7).unwrap()).unwrap()).unwrap(),
333755
);
assert_eq!(
part2(parse(parse::data(2021, 7).unwrap()).unwrap()).unwrap(),
94017638
);
}
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