83 lines
1.8 KiB
Rust
83 lines
1.8 KiB
Rust
use std::fmt::Write;
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use anyhow::{anyhow, bail, Result};
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const INPUT: &str = include_str!("../input/day01.txt");
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pub fn run() -> Result<String> {
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let mut res = String::with_capacity(128);
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writeln!(res, "part 1: {}", part1(INPUT)?)?;
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writeln!(res, "part 2: {}", part2(INPUT)?)?;
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Ok(res)
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}
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fn part1(input: &str) -> Result<i64> {
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Ok(input
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.chars()
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.filter_map(|c| match c {
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'(' => Some(1),
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')' => Some(-1),
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_ => None,
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})
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.sum())
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}
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fn part2(input: &str) -> Result<usize> {
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let mut sum = 0;
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let mut res = 0;
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for (i, c) in input.chars().enumerate() {
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match c {
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'(' => sum += 1,
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')' => sum -= 1,
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_ => bail!("unidentified character in input: {}", c),
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};
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if sum < 0 {
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res = i + 1;
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break;
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}
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}
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match res {
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0 => Err(anyhow!("never reached the basement...")),
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_ => Ok(res),
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}
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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(), 0);
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assert_eq!(part1("()()").unwrap(), 0);
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assert_eq!(part1("(((").unwrap(), 3);
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assert_eq!(part1("(()(()(").unwrap(), 3);
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assert_eq!(part1("))(((((").unwrap(), 3);
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assert_eq!(part1("())").unwrap(), -1);
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assert_eq!(part1("))(").unwrap(), -1);
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assert_eq!(part1(")))").unwrap(), -3);
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assert_eq!(part1(")())())").unwrap(), -3);
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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(), 74);
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}
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#[test]
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fn part2_provided() {
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assert_eq!(part2(")").unwrap(), 1);
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assert_eq!(part2("()())").unwrap(), 5);
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}
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#[test]
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fn part2_real() {
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assert_eq!(part2(INPUT).unwrap(), 1795);
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}
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}
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