2024/day03.rs


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#![allow(dead_code)]
#![allow(unused_variables)]
#![allow(unused_mut)]
use regex::Regex;
use std::env;
use std::fs::File;
use std::io::Read;

fn main() {
    let args: Vec<String> = env::args().collect();
    let filename = if args.len() == 1 {
        "in/".to_owned() + args[0].split('/').last().unwrap() + ".pzl"
    } else {
        args[1].clone()
    };
    let mut f = File::open(filename).expect("cannot open file");
    let mut content = String::new();
    f.read_to_string(&mut content).expect("cannot read file");
    let lines = content.trim_end().split("\n");

    let re = Regex::new(r"mul\(([0-9]+),([0-9]+)\)").unwrap();
    let res1 = lines
        .clone()
        .map(|line| {
            re.captures_iter(line)
                .map(|caps| {
                    let p = |n| caps.get(n).unwrap().as_str().parse::<i32>().unwrap();
                    p(1) * p(2)
                })
                .sum::<i32>()
        })
        .sum::<i32>();

    let re2 = Regex::new(r"^mul\(([0-9]+),([0-9]+)\)").unwrap();
    let mut res2 = 0;
    let mut valid = true;
    for line in lines {
        for i in 0..line.len() {
            if line[i..].starts_with("do()") {
                valid = true;
            } else if line[i..].starts_with("don't()") {
                valid = false;
            } else if valid && re2.is_match(&line[i..]) {
                let cap = re2.captures(&line[i..]).unwrap();
                let p = |n| cap.get(n).unwrap().as_str().parse::<i32>().unwrap();
                res2 += p(1) * p(2);
            }
        }
    }

    println!("res1: {}", res1);
    println!("res2: {}", res2);
    assert_eq!(res1, 162813399);
    assert_eq!(res2, 53783319);
}