leetcode Question 84: Reverse Integer

Reverse Integer

Reverse digits of an integer.

Example1: x = 123, return 321
Example2: x = -123, return -321

Analysis:

Simple question. Just be careful with the last digit and positive/negative.
Also be careful with the corner cases.
Idea is to keep x/10 for the original int and *10 for the result int + x%10.


Note that in Python, when compute -1/10 the result is -1 not the expected 0. 
This is because the "floor" function for the int division. 
E.g.,  math.floor(0.89) = 0
          math.floor(-0.89) = -1


So I check the positive and negative sign in the python code.
The number 214748364 in python code is the maxint/10 = 2147483647/10.

Code(C++):

class Solution {
public:
    int reverse(int x) {
        int  res = 0;
        while (x!=0){
            if (res > INT_MAX/10 || res < INT_MIN/10){
                return 0;
            }
            res = res*10+ x%10;
            x= x/10;
        }
        return res;
    }
};

Code (Python):

class Solution:
    # @return an integer
    def reverse(self, x):
        res = 0
        if x>=0:
            pos = True
        else:
            pos  = False
            x = -x
        while not x == 0:
            if res > 214748364:
                return 0
            else:
                res = res*10 + x%10
                x = x/10
        if pos:
            return res
        else:
            return -res