9、Palindrome Number

最新推荐文章于 2022-03-10 15:20:06 发布

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本文探讨了在不使用额外空间的情况下判断一个整数是否为回文数的方法。文章给出了一种解决方案，通过反转整数并比较原数与反转后的数来判断其是否为回文。同时讨论了处理负数和整数溢出的情况。

Determine whether an integer is a palindrome. Do this without extra space.

click to show spoilers.

Some hints:

Could negative integers be palindromes? (ie, -1)

If you are thinking of converting the integer to string, note the restriction of using extra space.

You could also try reversing an integer. However, if you have solved the problem "Reverse Integer", you know that the reversed integer might overflow. How would you handle such case?

There is a more generic way of solving this problem.

Math

bool isPalindrome(int x) {
    //此题限制不能使用额外空间，所以不能把整数转换为字符串,负数不能算是对称的
        if (x < 0)
            return false;
        int y = x;
        int result = 0, temp = INT_MAX / 10;
        while (x)
        {
            if (result > temp || result < 0)
            {
                result = -1;
                break;
            }
            result = result * 10 +  x % 10;
            x /= 10;
        }
        return y == result; 
    }