Function convolution_gcd

pub fn convolution_gcd<T>(f: Vec<T>, g: Vec<T>) -> Vec<T>
where
    T: Copy + Add<Output = T> + Sub<Output = T> + Mul<Output = T>,

$\mathtt{a_{\gcd (i, j)}} = \sum \mathtt{f_{i}} * \mathtt{g_{j}}$を満たすaを求める。