advent of code 2020, day 1

one.rs

use std::fs::File;
use std::io::{self, BufRead};
use std::path::Path;
use itertools::iproduct;

fn main() {
    if let Ok(lines) = read_lines("./input.txt") {

        let nums : Vec<i32> = lines.map(|l| l.unwrap().parse::<i32>().unwrap()).collect();
        
        for (i, j, k) in iproduct!(&nums, &nums, &nums) {

            if (i + j + k) == 2020 {
                println!("{} * {} * {} = {}", i , j, k, (i * j * k));
            }
         }
    }

}

// The output is wrapped in a Result to allow matching on errors
// Returns an Iterator to the Reader of the lines of the file.
fn read_lines<P>(filename: P) -> io::Result<io::Lines<io::BufReader<File>>>
where P: AsRef<Path>, {
    let file = File::open(filename)?;
    Ok(io::BufReader::new(file).lines())
}