palindrome_length.py

'''
Number is a palindrome if it is equal to the number with
digits in reversed order. For example, 5, 44, 171, 4884
are palindromes and 43, 194, 4773 are not palindromes.

Write a method palindrome_chain_length which takes a positive
number and returns the number of special steps needed to obtain a palindrome.
The special step is: "reverse the digits, and add to the original number".
If the resulting number is not a palindrome, repeat the procedure with
the sum until the resulting number is a palindrome.

If the input number is already a palindrome, the number of steps is 0.

Input will always be a positive integer.

For example, start with 87:

87 + 78 = 165; 165 + 561 = 726; 726 + 627 = 1353; 1353 + 3531 = 4884

4884 is a palindrome and we needed 4 steps to obtain it,
so palindrome_chain_length(87) == 4
'''

def palindrome_chain_length(n):
    # parameter n is a positive integer
    # your function should return the number of steps
    s=str(n)
    k=0
    while s!=s[::-1]:
        s=str(int(s)+int(s[::-1]))
        k+=1
    return k