```
public class Solution {
public boolean isPalindrome(int x) {
if(x<0)
return false;
int len = Integer.toString(x).length();
int i = (int)Math.pow(10,len-1);
int j= (int)Math.pow(10,1);
for(;;){
if(x/i!=x%j){
return false;
}else if(i>j){
x= x%i;
x/=j;
i=i/100;
}else{
return true;
}
}
}
}
```

The running times seems to fluctuate but passed all cases in less than 250ms.