Reverse Integer

依据加强的测试用例，很多参考已经不能通过。

当中要明白，如果，x是Integer.MIN_VALUE，Math.abs()仍只返回Integer.MIN_VALUE

public class Solution {
public int reverse(int x) {

if (x > -10 && x < 10) {
return x;
}
if (x == Integer.MAX_VALUE) {
return 0;
}
if (x == Integer.MIN_VALUE) {
return 0;
}
boolean positive = true;
int num = x;
if (x < 0) {
positive = false;
//num = Math.abs(x);
//num = -x;
num = 0-x;
}
String strN = String.valueOf(num);
StringBuilder sb = new StringBuilder(strN);
strN = sb.reverse().toString();
double dN = Double.valueOf(strN);
if (!positive) {
dN = -dN;
}
if (dN > Integer.MAX_VALUE) {
return 0;
}
if (dN < Integer.MIN_VALUE) {
return 0;
}
return (int) dN;
}
}