use rayon::prelude::*;

fn sum_squares(input: &[i32]) -> i32 {
    input.iter()
        .map(|i| i * i)
        .sum()
}

fn par_sum_squares(input: &[i32]) -> i32 {
    input.par_iter() // <-- just change that!
        .map(|i| i * i)
        .sum()
}