backward_and_forward

solution.py

# write a function answer(n) which returns the smallest positive integer base b, at least 2, 
# in which the integer n is a palindrome. The input n will satisfy "0 <= n <= 1000."
def answer(n):
   
   base = 1
   num1 = -1
   num2 = 0
   
   while num1 != num2:
    base = base + 1
    num1 = int(numberToBase(str(n), base))
    num2 = int(str(num1)[::-1])
    
   return base 
   
def numberToBase(n, b):
    
    n = int(n, 0)
    
    if n == 0:
        return "0"
    digits = []
    while n:
        digits.append(int(n % b))
        n /= b
    return ''.join(str(x) for x in digits[::-1])

answer(42) -> Base 4
answer(0) - > base 2

run on http://pythonfiddle.com/