def dec_to_bin(nb_dec):
q, r = nb_dec // 2, nb_dec % 2
if q == 0:
return str(r)
else:
return dec_to_bin(q) + str(r)
def bin_to_dec(nb_bin):
if nb_bin == '0':
return 0
elif nb_bin == '1':
return 1
else:
if nb_bin[-1] == '0':
bit_droit = 0
else:
bit_droit = 1
return 2 * bin_to_dec(nb_bin[:-1]) + bit_droit