71 lines
1.8 KiB
Rust
71 lines
1.8 KiB
Rust
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use crate::puzzle::Puzzle;
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pub const PUZZLE: Puzzle<Vec<(Direction, i32)>, i32, 2> = Puzzle {
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number: 1,
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parser: |input| {
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input
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.lines()
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.filter(|line| !line.is_empty())
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.map(|line| {
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let d = match line.chars().next().unwrap() {
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'L' => Direction::L,
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'R' => Direction::R,
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c => panic!("Unknown direction: {}", c),
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};
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let i: i32 = line[1..].parse().unwrap();
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(d, i)
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})
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.collect()
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},
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parts: [
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|instructions| {
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let mut p = 50;
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let mut r = 0;
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for (d, i) in instructions {
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let (_, p1) = step(*i, *d, p);
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if p1 == 0 {
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r += 1;
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}
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p = p1;
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}
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r
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},
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|instructions| {
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let mut p = 50;
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let mut r = 0;
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for (d, i) in instructions {
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let (c, p1) = step(*i, *d, p);
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let c1 = match d {
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Direction::R => c.abs(),
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Direction::L => {
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if p == 0 {
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c.abs() - 1
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} else if p1 == 0 {
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c.abs() + 1
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} else {
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c.abs()
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}
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}
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};
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r += c1;
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p = p1;
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}
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r
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},
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],
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};
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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pub enum Direction {
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L,
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R,
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}
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fn step(i: i32, d: Direction, p: i32) -> (i32, i32) {
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let p1 = match d {
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Direction::L => p - i,
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Direction::R => p + i,
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};
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(p1.div_euclid(100), p1.rem_euclid(100))
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}
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