leetcode_9_Palindrome Number

描述：

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.

思路：

很简单粗暴的思路就是将整数转换为StringBuilder，然后前面和后面的字符分别相比，直至前面和后面的下标相遇程序终止，任何一次比较不想等就不成立。但上面说without extra space，为啥我的程序能通过？好吧，程序不算真的通过，我用到了额外的存储空间。

代码：

public static boolean isPalindrome(int x) {        if(x<0)        return false;        boolean flag=true;        StringBuilder sBuilder=new StringBuilder(Integer.toString(x));        int len=sBuilder.length();        int i=0,j=len-1;        while(i<j)        {        if(sBuilder.charAt(i)!=sBuilder.charAt(j))        {        flag=false;        break;        }        else        {        i++;        j--;        }        }        return flag;    }

结果：