Reverse Integer

Reverse digits of an integer.

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

取模就ok。

int reverse(int x){    int res=0;    int pre=1;    if(x<0)    pre=-1;    int absx=abs(x);    while (absx)    {        res = res*10 + absx%10;        absx/= 10;    }    return pre*res;}