LeetCode——009 Palindrome Number

Posted 2021-03-09 自由の翼

Description

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?

//水题咯
bool isPalindrome(int x) {
    if (x == 0)return true;
    if (x < 0 || (x % 10 == 0))return false;//负数和尾数为0都不是回文数字
    double num = 0;
    int s = x;
    while (x > 0) {
        num = 10 * num + x % 10;
        x = x / 10;
    }
    if (num == s)return true;
    else return false;
}