leetcode 9. Palindrome Number

class Solution {
public:
    bool isPalindrome(int x) {
        if(x < 0) return false;
        int a1 = 1;
        while(a1<=x/10)a1*=10;
        
        while(x > 0){
            if(x/a1!=x%10)return false;
            x-=x/a1*a1;
            x/=10;
            a1/=100;
        }
        return true;
    }
};