9. Palindrome Number

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

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判断一个整数是否为回文。首先负数不是回文，然后题目要求不能有额外的空间，因此不能用栈的办法，也不能保存每个位数的数字，只能通过扫描整数位置，并进行前后判断。

如下所示：

class Solution {    public boolean isPalindrome(int x) {        if (x < 0){            return false;        }        int y = x, z = x;        long indexRight = 1;        while (y != 0){            indexRight = indexRight*10;            y = y/10;        }        int highVal = 0, lowVal = 0, indexLeft = 1;        while (indexRight != 1&&indexRight >= indexLeft){            highVal = (int)(z/(indexRight/10))%10;            lowVal = (int)(z/indexLeft)%10;            if (highVal != lowVal){                return false;            }            indexRight = indexRight/10;            indexLeft *= 10;        }        return true;    }}