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leetcode 007: reverse integer

https://leetcode.com/problems/reverse-integer/

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problem:

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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.

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start code (c++)

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class Solution {
public:
    int reverse(int x) {
        
    }
};

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solution 1:

我的思路：
请考虑溢出， 一个 int 型能够表示的数值范围是: [−2^31, 2^31 − 1]

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class Solution {
public:
    int reverse(int x) {
        int sign = 1;
        int isOverflow = 0;
        int max = 2147483647;
        int min = -2147483648;
        if (x == min)
            return 0;
        
        if (x < 0){
            x = -x;
            sign = -1;
        }
        
        int result = 0;
        while (x != 0){
            int digit = x % 10;
            if (result > max / 10 || (result * 10) > (max - digit)){
                isOverflow = 1;
                break;
            }
            result = result * 10 + digit;
            x = x / 10;
        }
        if (isOverflow)
            return 0;
        return sign * result;
    }
};

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