2018: day05: part 1
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aoc2018/input/day05.txt
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1
aoc2018/input/day05.txt
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63
aoc2018/src/day05.rs
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63
aoc2018/src/day05.rs
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use super::Result;
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const INPUT: &str = include_str!("../input/day05.txt");
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pub fn run() -> Result<()> {
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println!("part 1: {}", part1(INPUT)?);
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Ok(())
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}
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fn same_type(a: char, b: char) -> bool {
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a.to_ascii_lowercase() == b.to_ascii_lowercase()
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}
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fn part1(input: &str) -> Result<usize> {
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let mut res = String::with_capacity(input.len());
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// tracks last character of string
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let mut last: Option<char> = None;
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for next in input.chars() {
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match last {
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Some(elem) => {
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// if same type but different polarity
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if same_type(elem, next) && elem != next {
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// drop both elem and next
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last = res.pop();
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} else {
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// consider elem "safe" to push
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res.push(elem);
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last = Some(next);
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}
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}
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None => {
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last = Some(next);
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}
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}
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}
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// add last character to string if exists
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if let Some(c) = last {
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res.push(c);
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}
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Ok(res.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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const PROVIDED: &str = "dabAcCaCBAcCcaDA";
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#[test]
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fn part1_provided() {
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assert_eq!(part1(PROVIDED).unwrap(), 10);
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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(), 10638);
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}
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}
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@ -1,6 +1,7 @@
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pub mod day01;
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pub mod day02;
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pub mod day03;
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pub mod day05;
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pub type Result<T> = std::result::Result<T, Box<dyn std::error::Error>>;
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@ -3,11 +3,12 @@ use std::env;
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use aoc2018::day01;
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use aoc2018::day02;
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use aoc2018::day03;
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use aoc2018::day05;
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use aoc2018::Result;
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fn main() -> Result<()> {
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let days: &[fn() -> Result<()>] = &[day01::run, day02::run, day03::run];
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let days: &[fn() -> Result<()>] = &[day01::run, day02::run, day03::run, day05::run];
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let mut args = env::args();
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args.next();
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