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2020: day23: refacto cup access

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This commit is contained in:
Antoine Martin 2020-12-24 01:25:42 +01:00
parent e341008746
commit 022ca7daab
1 changed files with 13 additions and 13 deletions
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26
aoc2020/src/day23.rs
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@ -33,8 +33,8 @@ fn part2(input: &str) -> Result<usize> {
cup_circle.step();
}
let first = cup_circle.get_next_cup(1);
let second = cup_circle.get_next_cup(first);
let first = *cup_circle.next_cup(1);
let second = *cup_circle.next_cup(first);
Ok(first * second)
}
@ -165,21 +165,21 @@ struct FastCupCircle {
}
impl FastCupCircle {
fn get_next_cup(&self, cup: usize) -> usize {
self.cups[cup - 1]
fn next_cup(&self, cup: usize) -> &usize {
&self.cups[cup - 1]
}
fn set_next_cup(&mut self, cup: usize, next: usize) {
self.cups[cup - 1] = next;
fn next_cup_mut(&mut self, cup: usize) -> &mut usize {
&mut self.cups[cup - 1]
}
fn remove_next_3(&mut self, cup: usize) -> [usize; 3] {
let first = self.get_next_cup(cup);
let second = self.get_next_cup(first);
let third = self.get_next_cup(second);
let first = *self.next_cup(cup);
let second = *self.next_cup(first);
let third = *self.next_cup(second);
// shortcut the links to remove them from the loop temporarily
self.set_next_cup(cup, self.get_next_cup(third));
*self.next_cup_mut(cup) = *self.next_cup(third);
[first, second, third]
}
@ -215,12 +215,12 @@ impl FastCupCircle {
// The links from first to second and from second to third haven't changed, no need to
// update them
let [first, _, third] = removed_cups;
self.set_next_cup(third, self.get_next_cup(destination));
self.set_next_cup(destination, first);
*self.next_cup_mut(third) = *self.next_cup(destination);
*self.next_cup_mut(destination) = first;
// The crab selects a new current cup: the cup which is immediately clockwise of the current
// cup.
self.current = self.get_next_cup(self.current);
self.current = *self.next_cup(self.current);
}
}