Determine whether an integer is a palindrome. Do this without extra space.
Solution：
class Solution {
public:
bool isPalindrome(int x) {
if(x<0|| (x!=0 &&x%10==0)) return false;
int y=0;
while(x>y){
y=y*10+x%10;
x/=10;
}
return (y==x)||x==y/10;
}
};