AdventOfCode2023/src/solutions/day06.rs

use super::Solution;

pub struct Day06 {}

impl Solution for Day06 {
    fn part1(
        &self,
        input: &mut Vec<String>,
    ) -> Result<Box<dyn std::fmt::Display + Sync>, Box<dyn std::error::Error>> {
        let times: Vec<u64> = input[0]
            .split_whitespace()
            .skip(1)
            .map(|t| t.parse().unwrap())
            .collect();

        let distances: Vec<u64> = input[1]
            .split_whitespace()
            .skip(1)
            .map(|d| d.parse().unwrap())
            .collect();

        Ok(Box::new(self.num_winning_races(&times, &distances)?))
    }

    fn part2(
        &self,
        input: &mut Vec<String>,
    ) -> Result<Box<dyn std::fmt::Display + Sync>, Box<dyn std::error::Error>> {
        let times = vec![input[0]
            .split(":")
            .nth(1)
            .unwrap()
            .replace(" ", "")
            .parse::<u64>()?];

        let distances = vec![input[1]
            .split(":")
            .nth(1)
            .unwrap()
            .replace(" ", "")
            .parse::<u64>()?];

        Ok(Box::new(self.num_winning_races(&times, &distances)?))
    }

    fn get_day(&self) -> u8 {
        6
    }
}

impl Day06 {
    fn num_winning_races(
        &self,
        times: &Vec<u64>,
        distances: &Vec<u64>,
    ) -> Result<u32, Box<dyn std::error::Error>> {
        let mut beats = vec![];
        for (time, record) in times.iter().zip(distances.iter()) {
            let mut count: u32 = 0;
            for hold in 0..*time {
                let dist = (hold) * (time - hold);
                if dist > *record {
                    count += 1;
                }
            }
            beats.push(count);
        }

        Ok(beats.iter().fold(1, |acc, &b| acc * b))
    }
}

/// Test from puzzle input
#[cfg(test)]
mod test {
    use super::*;
    use crate::*;

    #[test]
    fn part1() {
        let challenge = day06::Day06 {};

        //Complete the Challenge
        let answer = challenge
            .part1(
                utils::get_input(challenge.get_day(), utils::InputType::Test1)
                    .unwrap()
                    .as_mut(),
            )
            .unwrap()
            .to_string();

        assert_eq!(answer, "288");
    }

    #[test]
    fn part2() {
        let challenge = day06::Day06 {};

        //Complete the Challenge
        let answer = challenge
            .part2(
                utils::get_input(challenge.get_day(), utils::InputType::Test2)
                    .unwrap()
                    .as_mut(),
            )
            .unwrap()
            .to_string();

        assert_eq!(answer, "71503");
    }
}