LeetCode:Reverse Integer

題目連接

Reverse digits of an integer.

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

 

Have you thought about this?

Here are some good questions to ask before coding. Bonus points for you if you have already thought through this!

If the integer's last digit is 0, what should the output be? ie, cases such as 10, 100.

Did you notice that the reversed integer might overflow? Assume the input is a 32-bit integer, then the reverse of 1000000003 overflows. How should you handle such cases?

Throw an exception? Good, but what if throwing an exception is not an option? You would then have to re-design the function (ie, add an extra parameter)

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leetcode的測試樣例中彷佛沒有翻轉後溢出的狀況。                     本文地址

class Solution {
public:
    int reverse(int x) {
        bool isPositive = true;
        if(x < 0){isPositive = false; x *= -1;}
        long long res = 0;//爲了防止溢出，用long long
        while(x)
        {
            res = res*10 + x%10;
            x /= 10;
        }
        if(res > INT_MAX)return isPositive ? INT_MAX : INT_MIN;
        if(!isPositive)return res*-1;
        else return res;
    }
};

 

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