9. Palindrome Number

题目描述

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?

Qiang的思路

class Solution:
    def isPalindrome(self, x: int) -> bool:
        if x < 0:
            return False
        _x = x
        tmp = 0
        while x != 0:
            tmp = tmp * 10 + x % 10
            x = x // 10
        return tmp == _x

class Solution {
public:
    bool isPalindrome(int x) {
        if(x < 0)
            return false;
        int _x = x;
        long long tmp = 0;
        while(_x != 0){
            tmp = tmp * 10 + _x % 10;
            _x = _x / 10;
        }
        return x == tmp;
    }
};