9. Palindrome Number

package LeetCode_9

/**
 * 9. Palindrome Number
 * https://leetcode.com/problems/palindrome-number/
 * Given an integer x, return true if x is palindrome integer.
An integer is a palindrome when it reads the same backward as forward. For example, 121 is palindrome while 123 is not.
Example 1:
Input: x = 121
Output: true

Example 2:
Input: x = -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: x = 10
Output: false
Explanation: Reads 01 from right to left. Therefore it is not a palindrome.

Example 4:
Input: x = -101
Output: false
 * */
class Solution {
    /*
    * solution: x compare with reversed x
    * */
    fun isPalindrome(x: Int): Boolean {
        if (x < 0) {
            return false
        }
        var n = x
        var reverseNum = 0
        while (n > 0) {
            reverseNum = reverseNum * 10 + n % 10
            n /= 10
        }
        return x == reverseNum
    }
}