// lovely
//hi
//hi
fn calc_gpa(grades: &str) -> f64 {
    let grade_points: Vec<f64> = grades
        .split_whitespace()
        .flat_map(str::parse)
        .map(|grade| match grade {
            90..=100 => 4.0,
            80..=89 => 3.0,
            70..=79 => 2.0,
            60..=69 => 1.0,
            _ => 0.0
        })
        .collect();
    
    grade_points.iter().sum::<f64>() / grade_points.len() as f64
}