LeetCode Ex09 Palindrome Number

Palindrome Number

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

Example 1:
Input: 121
Output: true

Example 2:
Input: -121
Output: false
Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome.

Example 3:
Input: 10
Output: false
Explanation: Reads 01 from right to left. Therefore it is not a palindrome.

题目

该题要求判断一个数是否是回文数，主要和Leetcode07联动。若一个数是负数，则肯定不是回文数；否则判断一个数翻转后是否和原来相等即可，需要注意的是翻转后是否以0为开头，

    public static 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);
    }