9. Palindrome Number Hardness: \(\color{green}\textsf{Easy}\) Ralated Topics: Math 一、題目 Given an integer x, return true if x is palindrome number. An integer is a palindrome when it reads the same backward as forward. For example, 121 is a palindrome while 123 is not. Example 1: Input: x = 121 Output: true Explanation: 121 reads as 121 from left to right and from right to left. Example 2: Input: x = -121 Output: false Explanation: From left to right, it reads -121....