题目描述：
Reverse digits of an integer.
Example1: x = 123, return 321 Example2: x = -123, return -321
click to show spoilers.
Note: The input is assumed to be a 32-bit signed integer. Your function should return 0 when the reversed integer overflows.
采用方案：
public int reverse(int x) {
long rev= 0;
while( x != 0){
rev= rev*10 + x % 10;
x= x/10;
if( rev > Integer.MAX_VALUE || rev < Integer.MIN_VALUE)
return 0;
}
return (int) rev;
}
