Palindrome Number

题目：

Determine whether an integer is a palindrome. Do this without extra space

 

解答：

First, compare the first and last
digit. If they are not the same, it must not be a palindrome. If they are the same, chop off
one digit from both ends and continue until you have no digits left, which you conclude
that it must be a palindrome

 

public boolean isPalindrome(int x) {
    if(x < 0) {
        return false;
    }

    int div = 1;
    while(x / div >= 10) {
        div = div * 10;
    }

    while(x != 0) {
        int l = x / div;
        int r = x % 10;
        if(l != r) {
            return false;
        }

        x = (x % div) / 10;
        div = div / 100;
    }

    return true;
}