LeetCode 7. Reverse Integer

Given a 32-bit signed integer, reverse digits of an integer.

Example 1:

Input: 123
Output: 321

Example 2:

Input: -123
Output: -321

Example 3:

Input: 120
Output: 21

Note:

Assume we are dealing with an environment which could only store integers within the 32-bit signed integer range: [−231,  231 − 1]. For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.

C

int reverse(int x) {
    long int rev = 0;
    while(x){
        rev = rev*10+x%10;
        x /= 10;
    }
    if(rev<INT_MIN||rev>INT_MAX){
        return 0;
    }
    return rev;
}

C++

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

Java

class Solution {
    public int reverse(int x) {
        long rev = 0;
        while(x!=0){
            rev = rev*10+x%10;
            x /= 10;
        }
        if(rev<-2147483648||rev>2147483647)return 0;
        return (int)rev;
    }
}

Python

class Solution:
    def reverse(self, x):
        """
        :type x: int
        :rtype: int
        """
        sign = 1
        if x<0:sign*=-1
        x = sign*int(str(sign*x)[::-1])
        if -2147483649<x<2147483648:return x
        return 0