This is my solution to the first task of the Advent of Code 2023.

The task description is:

On each line, the calibration value can be found by combining the first digit and the last digit (in that order) to form a single two-digit number.

For example:

1abc2
pqr3stu8vwx
a1b2c3d4e5f
treb7uchet

In this example, the calibration values of these four lines are 12, 38, 15, and 77. Adding these together produces 142.

Consider your entire calibration document. What is the sum of all of the calibration values?

Here is my solution, which provides the correct sum (at least I passed the task):

use std::fs::read_to_string;
use regex::Regex;

fn main() {
    let re = Regex::new(r"^[\D]*(\d)(|.*(\d))\D*$").unwrap();
    let mut sum: u32 = 0;

    for line in read_to_string("calibration_data.txt").unwrap().lines() {
        println!("{line}");
        let Some(caps) = re.captures(line) else {
            panic!("no match! in line {line}");
        };
        let first: &str = &caps.get(1).map_or("0", |m| m.as_str());
        let second: &str = &caps.get(3).map_or(first, |m| m.as_str());
        let mut compound: String = String::new();
        compound.push_str(first);
        compound.push_str(second);
        println!("{first} + {second} = {compound}");
        let compound: u32 = compound.parse().unwrap();
        sum += compound;
    }

    println!("***********************");
    println!("Calibration sum: {sum}");
    println!("***********************");
}

Is there any way I could have done this better, especially regarding the extraction of the numbers from the text lines?

posted 4 months ago

CC BY-NC-SA 4.0

GeraldS‭

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