Reverse Integer

Leetcode-7

Posted by Evan on November 22, 2017

Reverse Integer

Question

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 hold integers within the 32-bit signed integer range. For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.

Answer

问题不算难,设置一个while然后求余并除应该可以得到结果

class Solution {
public:
    int reverse(int x) {
        int temp = x;
        int result = 0;
        while(temp) {
            result = result*10 + temp % 10;
            temp /= 10;
        }
        return result;
    }
};

但是题目有一个要求:机器是运行在32位的系统上的,溢出时需要改为0。
因此需要修改。

首先我们将结果改为long long的类型,再去判断结果是否超过32位的最值

long long result = 0;
...
return (result > INT_MAX || result < INT_MIN) ? 0 : result;