dec_to_bin.py

from math import log, floor


def dec_to_bin(N):
    if N == 0 or N == 1:
        return N
    String = ''
    Powers = []
    while N > 0:
        x = log(N, 2)
        x = floor(x)
        Powers.append(x)
        N -= 1<<x
    String = '0'*(max(Powers)+1)
    String = list(String) #string is immutable
    #So, 
    for x in Powers:
        String[-x-1] = '1'
    
    print(''.join(String))

def main():
    dec_to_bin(int(input("Enter a number: ")))

if __name__ == "__main__":
    main()