LeetCode_9: Palindrome Number

# 引言

题目链接：https://leetcode.com/problems/palindrome-number/description/

# 题目大意

判断一个数字是不是回文数字。

• Example

Input: 121
Output: true

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.

# 题解

# 一句话题解

一个数字为回文数字, 则对称点后半部分的翻转数字和前半部分的数值相等, 模拟判断即可(特判：负数和末尾为零的非零数字直接返回false)

复杂度 O(n)

# AC代码

c++版本

class Solution
{
  public:
    bool isPalindrome(int x)
    {
        if (0 == x)
        {
            return true;
        }
        if (x < 0 || 0 == x % 10)
        {
            return false;
        }
        int reverseNum = 0;
        while (reverseNum < x)
        {
            reverseNum = reverseNum * 10 + x % 10;
            x /= 10;
        }
        return reverseNum == x || reverseNum / 10 == x;
    }
};

go版本

func isPalindrome(x int) bool {
	if 0 == x {
		return true
	}
	if x < 0 || 0 == x%10 {
		return false
	}
	reverseNum := 0
	for reverseNum < x {
		reverseNum = reverseNum*10 + x%10
		x = x / 10
	}
	return reverseNum == x || reverseNum/10 == x
}