7. Reverse Integer

Description

Given a 32-bit signed integer, reverse digits of an integer.

Input: 123
Output:  321

Input: -123
Output: -321

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.

Solution

reverse一个整数，考虑到负数和溢出就行了

int reverse(int x) {
    long long n = 0;
    while (x) {
        n = n * 10 + x % 10;
        x /= 10;
    }
    return (n > INT_MAX || n < INT_MIN)? 0 : n;
}