9. Palindrome Number

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

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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.

题意：判断一个数是否为回文数。

思路：若x<0,则返回false，否则将其转化为字符串，然后在利用对称性判断。

代码：

class Solution {
    public boolean isPalindrome(int x) {
        if(x<0)
           return false;
         String s = Integer.toString(x);
        int length=s.length();
        for(int i=0;i<length/2;i++)
        {
            if(s.toCharArray()[i] !=s.toCharArray()[length-i-1])
                return false;
        }
        return true;
    }
}