7. Reverse Integer（python+cpp）（int范围的问题）

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题目：

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.

解释：
题目要求我们是在32位的环境中解决问题？？这如何知道是不是超出范围?辣鸡题目…
python代码：

class Solution(object):
    def reverse(self, x):
        """
        :type x: int
        :rtype: int
        """
        y=0
        if x<0:
            x=str(x)[1:]
            y=-int(x[::-1])
        else:
            y=int(str(x)[::-1])
        if y<-2**31 or y>2**31-1:
            y=0
        return y

c++代码：

#include <algorithm>
#include <cstdlib>
#include <string>
using namespace std;
class Solution {
public:
    int reverse(int x) {
        long result=0;
        bool flag=false;
        if (x<0)
            flag=true;
        x=abs(x);
        string s=to_string(x);
        std::reverse(s.begin(),s.end());
        result=atol(s.c_str());
        if (result<INT_MIN ||result>INT_MAX)
            return 0;
        return flag?-result:result;
    }
};

总结：