79 lines
1.8 KiB
Rust
79 lines
1.8 KiB
Rust
use std::str::FromStr;
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use color_eyre::eyre;
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use eyre::{eyre, ensure};
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use crate::lib::ParseLines;
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enum Direction {
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Forward,
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Up,
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Down,
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}
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struct MoveCmd {
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dir: Direction,
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value: i32,
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}
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impl<'a> FromStr for MoveCmd {
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type Err = eyre::Report;
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fn from_str(s: &str) -> Result<Self, Self::Err> {
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let parts: Vec<&str> = s.split_whitespace().collect();
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ensure!(parts.len() == 2, "Could not parse: \"{}\" (Wrong number of words)", s);
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let dir = match parts[0] {
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"forward" => Direction::Forward,
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"up" => Direction::Up,
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"down" => Direction::Down,
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_ => return Err(eyre!("Could not parse: \"{}\" (invalid axis)", s)),
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};
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let value = parts[1].parse::<i32>()?;
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Ok(MoveCmd{dir, value})
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}
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}
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pub fn part1(data: &str) -> eyre::Result<()> {
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let mut horiz = 0; // how many units forward
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let mut vert = 0; // how many units DOWN (so flipped)
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for res in data.parse_lines::<MoveCmd>() {
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let cmd = res?;
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match cmd.dir {
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Direction::Forward => horiz += cmd.value,
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Direction::Up => vert -= cmd.value,
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Direction::Down => vert += cmd.value,
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}
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}
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println!("One: {}", horiz * vert);
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Ok(())
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}
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pub fn part2(data: &str) -> eyre::Result<()> {
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let mut horiz = 0;
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let mut vert = 0;
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let mut aim = 0;
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for res in data.parse_lines::<MoveCmd>() {
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let cmd = res?;
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match cmd.dir {
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Direction::Down => aim += cmd.value, // flipped again
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Direction::Up => aim -= cmd.value,
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Direction::Forward => {
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horiz += cmd.value;
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vert += cmd.value * aim;
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}
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}
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}
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println!("Two: {}", horiz * vert);
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Ok(())
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}
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