use std::collections::BTreeMap;

struct SparsePoly {
    monomials: BTreeMap<Vec<i32>, f64>,
}

fn main() {
    let mut movie_reviews: BTreeMap<Vec<i32>, f32> = BTreeMap::new();
    movie_reviews.insert(vec![1, 2, 3], 1.0);
    movie_reviews.insert(vec![1, 2, 4], 2.0);

    for (powers, coeff) in movie_reviews {
        print!("Powers:");
        for pow in powers {
            print!(" {}", pow);
        }
        println!(" Coefficient: {}", coeff)
    }

    println!("Hello, world!");
}