Aoc-2023-Rust/src/day1.rs

// use itertools::Itertools;
use std::fs;

pub fn run() {
    println!("Day 1:");
    let input = fs::read_to_string("./inputs/day1.txt").expect("Could not read file");

    println!("\tPart 1: {}", part1(&input));
    println!("\tPart 2: {}", part2(&input));
}

fn part1(calibration_input: &str) -> usize {
    calibration_input
        .split("\n")
        .map(|line| {
            let digits = line.chars().filter(|c| c.is_digit(10)).collect::<String>();

            if digits.len() == 1 {
                digits.parse::<usize>().unwrap() * 11
            } else {
                let tens = digits.chars().nth(0).unwrap().to_digit(10).unwrap();
                let ones = digits.chars().last().unwrap().to_digit(10).unwrap();
                (tens * 10 + ones) as usize
            }
        })
        .into_iter()
        .sum()
}

fn part2(calibration_input: &str) -> usize {
    let word_to_digit_map: [(&str, usize); 9] = [
        ("one", 1),
        ("two", 2),
        ("three", 3),
        ("four", 4),
        ("five", 5),
        ("six", 6),
        ("seven", 7),
        ("eight", 8),
        ("nine", 9),
    ];

    calibration_input
        .split("\n")
        .map(|line| {
            let mut index_and_digit: Vec<(usize, usize)> = vec![];

            for (word, digit) in word_to_digit_map {
                for (index, _) in line.match_indices(word).collect::<Vec<_>>() {
                    index_and_digit.push((index, digit));
                }
            }

            for (index, c) in line.chars().enumerate() {
                match c.to_digit(10) {
                    Some(digit) => index_and_digit.push((index, digit as usize)),
                    None => continue,
                }
            }

            if index_and_digit.len() == 1 {
                index_and_digit[0].1 * 11
            } else {
                index_and_digit.sort_by(|a, b| a.0.cmp(&b.0));
                println!(
                    "{} {}",
                    &line,
                    index_and_digit[0].1 * 10 + index_and_digit.last().unwrap().1
                );

                index_and_digit[0].1 * 10 + index_and_digit.last().unwrap().1
            }
        })
        .into_iter()
        .sum()
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_1() {
        let input = "1abc2
        pqr3stu8vwx
        a1b2c3d4e5f
        treb7uchet";

        assert_eq!(part1(input), 142);
    }

    #[test]
    fn test_2() {
        let input = "two1nine
eightwothree
abcone2threexyz
xtwone3four
4nineeightseven2
zoneight234
7pqrstsixteen";

        assert_eq!(part2(input), 281);
    }
}