7. Reverse Integer

7. Reverse Integer

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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 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.

class Solution {
public:
    int reverse(int x) {
        int flag = 1;
        if(x < 0) flag = -1, x *= -1;
        long long sum = 0;
        while(x){
            sum = (sum * 10 + (x % 10));
            x /= 10;
        }
        long long ans = sum * flag;
        return (ans > INT_MAX || ans < INT_MIN)? 0 : ans;
    }
};