Treat the input int just like string, and split it into head tail character and a shorter palindrome string, so it can be solved recursively.

its time complexity is O(n)

```
class Solution(object):
def isPalindrome(self, x):
"""
:type x: int
:rtype: bool
"""
x = str(x) # convert int to string
if len(x) < 2: return True # base case
return x[0]==x[-1] and self.isPalindrome(x[1:-1])
```