文章目錄

• 1. 題目描述：
• 2. 思路分析：
• 3. Java程式碼：

1. 題目描述：

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.

Follow up:

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

2. 思路分析：

題目的意思是判斷一個數字是否是迴文數字，要求不要轉成字串進行求解。
思路就是找出該數字的前一半和後一半的逆序，比較是否相等，如果相等返回true，否則返回false。
注意

3. Java程式碼：

原始碼：見我GiHub主頁

程式碼：

public static boolean isPalindrome(int x) {
    if (x == 0) {
        return true;
    }

    if (x < 0 || x % 10 == 0) {
        return false;
    }

    int reverse = 0;
    while (x > reverse) {
        reverse = reverse * 10 + x % 10;
        x /=
 
 10;
    }

    return x == reverse || x == reverse / 10;
}