Answer by Aziz Alto for Convert int to binary string in Python

one-liner with lambda:

>>> binary = lambda n: '' if n==0 else binary(n/2) + str(n%2)

test:

>>> binary(5)'101'

EDIT:

but then :(

t1 = time()for i in range(1000000):     binary(i)t2 = time()print(t2 - t1)# 6.57236599922

in compare to

t1 = time()for i in range(1000000):'{0:b}'.format(i)t2 = time()print(t2 - t1)# 0.68017411232