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

 

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主要是获取整数的长度，然后两个指针分别从整数的两边进行比较，然后往中心移动，如果不相等就返回false，全部相等返回true

class Solution {public:    bool isPalindrome(int x) {        if (x < 0) {            return false;        }        int n = len_of_integer(x);        int left = n;        int right = 1;        while (left > right) {            int l_num = get_num_of_position(x, left);            int r_num = get_num_of_position(x, right);            if (l_num == r_num) {                left--;                right++;            } else {                return false;            }        }        return true;    }    int len_of_integer(int x) {        int n = 0;        while (x) {            x = x / 10;            n++;        }        return n;    }    int get_num_of_position(int x, int p) {        int m = pow(10, p);        int n = pow(10, p - 1);        int y = x % m;        return y / n;    }};