import org.lep.leetcode.parseint.IntegerParser;

/**

 * Source : https://oj.leetcode.com/problems/palindrome-number/

 *

 * Created by lverpeng on 2017/7/5.

 *

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

 *

 * 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.

 *

 */

public class IntPalindrome {

    /**

     * 负数可以自己决定是否进行判断，这里不进行判断，归为不是

     * 依次取出整数的第一位和最后一位比较

     * 第一位：整除

     * 最后一位：对10求余

     *

     * @param num

     * @return

     */

    public boolean isPalindrome (int num) {

        if (num < 0) {

            return false;

        }

        int base = 1;

        while (num / (base) >= 10) {

            base *= 10;

        }

        while (num != 0) {

            int left = num / base;

            int right = num % 10;

            if (left != right) {

                return false;

            }

            num = (num % base) / 10;

            base /= 100;

        }

        return true;

    }

    public static void main(String[] args) {

        IntPalindrome palindrome = new IntPalindrome();

        System.out.println(palindrome.isPalindrome(0));

        System.out.println(palindrome.isPalindrome(-101));

        System.out.println(palindrome.isPalindrome(1001));

        System.out.println(palindrome.isPalindrome(1234321));

        System.out.println(palindrome.isPalindrome(2147447412));

        System.out.println(palindrome.isPalindrome(5155));

        System.out.println(palindrome.isPalindrome(5552));

    }

}