99 lines
2.1 KiB
Rust
99 lines
2.1 KiB
Rust
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use std::collections::HashSet;
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use aoc::err;
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use aoc::Result;
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const INPUT: &str = include_str!("../input/day03.txt");
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pub fn run() -> Result<()> {
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println!("part 1: {}", part1(INPUT)?);
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println!("part 2: {}", part2(INPUT)?);
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Ok(())
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}
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fn part1(input: &str) -> Result<usize> {
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let mut houses = HashSet::new();
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let mut x = 0;
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let mut y = 0;
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houses.insert((x, y));
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for c in input.trim_end().chars() {
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match c {
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'>' => x += 1,
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'<' => x -= 1,
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'^' => y -= 1,
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'v' => y += 1,
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_ => return Err(err!("unidentified move: `{}`", c)),
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}
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houses.insert((x, y));
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}
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Ok(houses.len())
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}
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fn part2(input: &str) -> Result<usize> {
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let mut houses = HashSet::new();
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let mut santa_x = 0;
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let mut santa_y = 0;
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let mut robot_x = 0;
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let mut robot_y = 0;
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houses.insert((0, 0));
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for (i, c) in input.trim_end().chars().enumerate() {
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if i % 2 == 0 {
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match c {
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'>' => santa_x += 1,
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'<' => santa_x -= 1,
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'^' => santa_y -= 1,
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'v' => santa_y += 1,
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_ => return Err(err!("unidentified move: `{}`", c)),
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}
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houses.insert((santa_x, santa_y));
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} else {
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match c {
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'>' => robot_x += 1,
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'<' => robot_x -= 1,
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'^' => robot_y -= 1,
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'v' => robot_y += 1,
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_ => return Err(err!("unidentified move: `{}`", c)),
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}
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houses.insert((robot_x, robot_y));
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}
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}
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Ok(houses.len())
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn part1_provided() {
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assert_eq!(part1(">").unwrap(), 2);
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assert_eq!(part1("^>v<").unwrap(), 4);
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assert_eq!(part1("^v^v^v^v^v").unwrap(), 2);
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}
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#[test]
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fn part1_real() {
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assert_eq!(part1(INPUT).unwrap(), 2565);
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}
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#[test]
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fn part2_provided() {
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assert_eq!(part2("^v").unwrap(), 3);
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assert_eq!(part2("^>v<").unwrap(), 3);
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assert_eq!(part2("^v^v^v^v^v").unwrap(), 11);
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}
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}
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