example.rs

    fn backtrack<'a, T>(&self, a: &'a [T], b: &'a [T], i: usize, j: usize) -> Vec<&'a T>
            where T: Eq {

        if i == 0 || j == 0 {
            vec![]
        } else if a[i] == b[j] {
            let mut prefix_lcs = self.backtrack(a, b, i - 1, j - 1);
            prefix_lcs.push(&a[i]);

            prefix_lcs
        } else {
            if self.lengths[i][j - 1] > self.lengths[i - 1][j] {
                self.backtrack(a, b, i, j - 1)
            } else {
                self.backtrack(a, b, i - 1, j)
            }
        }
    }