-module(play).
-export([bits/1, perimeter/1, enclose/1]).

bits(S, N, D) when N == 0 ->
        S + D;
bits(S, N, D) ->
    bits(S+D, N div 2, N rem 2).

bits(N) -> bits(0, N, 0).


perimeter({circle, R}) ->
    2 * math:pi() * R;

perimeter({triangle, {S1, S2, S3}}) ->
    S1 + S2 + S3;

perimeter({square, S}) ->
    S * S;

perimeter({rectangle, {W, H}}) ->
    perimeter({parallelepiped, {W, W, H, H}});

perimeter({parallelepiped, {S1, S2, S3, S4}}) ->
    S1 + S2 + S3 + S4.