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Optimize 21/1

This commit is contained in:
kageru 2021-12-21 21:57:53 +01:00
parent 7cdb90bf8e
commit c19088f3cb
Signed by: kageru
GPG Key ID: 8282A2BEA4ADA3D2
1 changed files with 5 additions and 8 deletions
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13
2021/src/bin/day21.rs
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@ -10,18 +10,15 @@ fn part1((p1, p2): Parsed) -> usize {
.cycle()
.skip(1)
.step_by(3)
.enumerate()
.scan([(p1, 0), (p2, 0)], |mut scores, (round, die)| {
.zip(1..)
.scan([(p2, 0), (p1, 0)], |mut scores, (die, round)| {
let mut points = scores[round & 1].0 + die * 3;
// can’t use mod 10 because we actually want to keep the 10
while points > 10 {
points -= 10;
}
points -= (points - 1) / 10 * 10;
scores[round & 1].0 = points;
scores[round & 1].1 += points;
Some((round + 1, *scores))
Some((round, (scores[0].1, scores[1].1)))
})
.find_map(|(r, [(_, s1), (_, s2)])| (s1 >= 1000 || s2 >= 1000).then(|| r * 3 * (s1.min(s2) as usize)))
.find_map(|(r, (s1, s2))| (s1 >= 1000 || s2 >= 1000).then(|| r * 3 * (s1.min(s2) as usize)))
.unwrap()
}