Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward.

Example 1:

Input: 121Output: true

Example 2:

Input: -121Output: falseExplanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome.

Example 3:

Input: 10Output: falseExplanation: Reads 01 from right to left. Therefore it is not a palindrome.

Follow up:

Coud you solve it without converting the integer to a string?

 

解法一：把翻转过的数计算出来（我的方法）

解法二：只翻转一半

public boolean isPalindrome(int x) {    if (x<0 || (x!=0 && x%10==0)) return false;    int rev = 0;    while (x>rev){        rev = rev*10 + x%10;        x = x/10;    }    return (x==rev || x==rev/10);}