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Day 6 part 2 slightly faster over pre-rotate_left version.

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This commit is contained in:
Bill Thiede 2021-12-06 19:13:46 -08:00
parent 60b77d5d3d
commit 343707c63c
1 changed files with 10 additions and 4 deletions
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14
2021/src/day6.rs
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@ -88,10 +88,16 @@ fn part2(input: &str) -> Result<usize> {
.into_iter() .into_iter()
.for_each(|n| counts[n] += 1); .for_each(|n| counts[n] += 1);
for _ in 0..256 { for _ in 0..256 {
let ready = counts[0]; let mut tmp = [0; 9];
counts.rotate_left(1); for (i, c) in counts.iter().enumerate() {
counts[6] += ready; if i == 0 {
counts[8] = ready; tmp[6] = *c;
tmp[8] = *c;
} else {
tmp[i - 1] += *c;
}
}
counts = tmp;
} }
Ok(counts.iter().sum()) Ok(counts.iter().sum())
} }