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Do no actually need lcm

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Dreaded_X 2022-12-11 18:08:56 +01:00
parent afd943fcd7
commit 8ab48001ea
1 changed files with 1 additions and 19 deletions
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20
2022/src/bin/day11.rs
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@ -44,24 +44,6 @@ mod tests {
} }
} }
fn gcd(a: i64, b: i64) -> i64 {
match ((a, b), (a & 1, b & 1)) {
((x, y), _) if x == y => y,
((0, x), _) | ((x, 0), _) => x,
((x, y), (0, 1)) | ((y, x), (1, 0)) => gcd(x >> 1, y),
((x, y), (0, 0)) => gcd(x >> 1, y >> 1) << 1,
((x, y), (1, 1)) => {
let (x, y) = (min(x, y), max(x, y));
gcd((y - x) >> 1, x)
}
_ => unreachable!(),
}
}
fn lcm(a: i64, b: i64) -> i64 {
a * b / gcd(a, b)
}
#[derive(Debug, Copy, Clone)] #[derive(Debug, Copy, Clone)]
enum Operation { enum Operation {
Add(i64), Add(i64),
@ -144,7 +126,7 @@ fn step(monkeys: &mut Vec<Monkey>, div: i64, reducer: i64) {
fn solution(input: &str, rounds: i32, div: i64) -> i64 { fn solution(input: &str, rounds: i32, div: i64) -> i64 {
let mut monkeys: Vec<Monkey> = input.split("\n\n").map(|line| line.parse().unwrap()).collect(); let mut monkeys: Vec<Monkey> = input.split("\n\n").map(|line| line.parse().unwrap()).collect();
let reducer = monkeys.iter().fold(1, |acc, monkey| lcm(acc, monkey.divisor)); let reducer = monkeys.iter().fold(1, |acc, monkey| acc * monkey.divisor);
for _ in 0..rounds { for _ in 0..rounds {
step(&mut monkeys, div, reducer); step(&mut monkeys, div, reducer);