0 QTRS
rev(nil) → nil rev(++(x, y)) → ++(rev1(x, y), rev2(x, y)) rev1(x, nil) → x rev1(x, ++(y, z)) → rev1(y, z) rev2(x, nil) → nil rev2(x, ++(y, z)) → rev(++(x, rev(rev2(y, z))))