AOC 23 Day 1

main.rs

use std::env;
use std::fs::File;
use std::io::{self, BufRead};

fn main() {
    let args: Vec<String> = env::args().collect();
    if args.len() != 2 {
        eprintln!("Usage: {} <filename>", args[0]);
        std::process::exit(1);
    }
    let filename = &args[1];

    let file = match File::open(filename) {
        Ok(file) => file,
        Err(error) => {
            eprintln!("Error opening file {}: {}", filename, error);
            std::process::exit(1);
        }
    };

    let reader = io::BufReader::new(file);

    let mut accumulator : u32 = 0;
    for (line_number, line) in reader.lines().enumerate() {
        match line {
            Ok(line_content) => {
                let numbers = part2(
                    line_number + 1,
                    line_content.clone()
                );
                if numbers.len() != 0 {
                    println!("Numbers: {:?} / {}", numbers, line_content);
                    accumulator += format!("{}{}",numbers[0], numbers[numbers.len()-1]).parse::<u32>().expect(format!("Line {} does not produce a number", line_number).as_str());
                } 
                ()
            }
            Err(error) => {
                eprintln!("Error reading line {}: {}", line_number + 1, error);
                ()
            } 
        }
    }
    println!("Total = {}", accumulator);
}

fn part1(_line_number: usize, line_content: String) -> Vec<char> {
    let chars: Vec<char> = line_content.chars().collect(); 
    let mut result: Vec<char> = Vec::new();

    for i in chars.iter() {
        match i { 
            '1'..='9' => result.push(*i),
            _ => ()
        }
    }

    return result;
}

fn part2(_line_number: usize, line_content: String) -> Vec<char> {
    let chars: Vec<char> = line_content.chars().collect();
    let mut result: Vec<char> = Vec::new();

    for (pos, i) in chars.iter().enumerate() {
        match i { 
            '1'..='9' => result.push(*i),
            _ => {
                if pos+4 < chars.len() {
                    match &line_content[pos..=pos + 4] {
                        "three" => result.push('3'),
                        "eight" => result.push('8'),
                        "seven" => result.push('7'),
                        _ => ()
                    }
                }
                if pos+3 < chars.len() {
                    match &line_content[pos..=pos + 3] {
                        "four" => result.push('4'),
                        "five" => result.push('5'),
                        "nine" => result.push('9'),
                        _ => ()
                    }
                }
                if pos+2 < chars.len() {
                    match &line_content[pos..=pos + 2] {
                        "one" => result.push('1'),
                        "two" => result.push('2'),
                        "six" => result.push('6'),
                        _ => ()
                    }
                }
            }
        }
    }

    return result;
}