Stefan Müller
64 lines
2.0 KiB
Rust
64 lines
2.0 KiB
Rust
use crate::solvers::Solver;
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use std::io::BufRead;
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pub struct SecretEntrance {}
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impl SecretEntrance {
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const START_POSITION: i32 = 50;
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const DIAL_SIZE: i32 = 100;
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const ZERO_POSITION: i32 = 0;
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const POSITIVE_SIGN_CHAR: char = 'R';
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const NEGATIVE_SIGN_CHAR: char = 'L';
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fn update_position(
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position: i32,
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distance: i32,
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mut zero_hits: u64,
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mut zero_passes: u64,
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) -> (i32, u64, u64) {
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let mut new_position = position + distance;
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let rounds = new_position.div_euclid(Self::DIAL_SIZE);
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zero_passes += u64::try_from(rounds.abs()).unwrap();
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new_position -= Self::DIAL_SIZE * rounds;
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if new_position == Self::ZERO_POSITION {
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zero_hits += 1;
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if position != Self::ZERO_POSITION && distance < 0 {
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zero_passes += 1;
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}
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} else if position == Self::ZERO_POSITION && distance < 0 {
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zero_passes -= 1;
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}
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(new_position, zero_hits, zero_passes)
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}
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}
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impl Solver for SecretEntrance {
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const PUZZLE_INDEX: u8 = 1;
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const PUZZLE_NAME: &'static str = "Secret Entrance";
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fn process_data<R: BufRead>(&self, reader: R) -> (u64, u64) {
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let mut position = Self::START_POSITION;
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let mut zero_hits = 0;
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let mut zero_passes = 0;
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let format: String = format!(
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"{{[{}{}]}}{{d}}",
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Self::POSITIVE_SIGN_CHAR,
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Self::NEGATIVE_SIGN_CHAR
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);
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for line in reader.lines().map_while(Result::ok) {
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let (sign, distance) = scan_fmt!(&line, &format, char, i32).unwrap();
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(position, zero_hits, zero_passes) = Self::update_position(
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position,
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if sign == Self::POSITIVE_SIGN_CHAR {
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distance
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} else {
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-distance
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},
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zero_hits,
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zero_passes,
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);
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}
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(zero_hits, zero_passes)
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}
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}
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