Classify the following polynomials based on their degree.
(i)$$ p(x)=3$$
(ii) $$p(y)=\frac{5}{2}y^2+1$$
(iii)$$p(x)=2x^3-x^2+4x+1$$
(iv)$$ p(x)=3x^2$$
(v)$$ p(x)=x+3$$
(vi) $$p(x)=-7$$
(vii) $$p(x)=x^3+1$$
(viii) $$p(x)=5x^2-3x+2$$
(ix)$$p(x)=4x$$
(x) $$p(x)=\dfrac {3}{2}$$
(xi) $$p(x)=\sqrt{3}x+1$$
(xii) $$p(y)=y^3+3y$$