leetcode-9-回文数

问题：

 

 

package com.nxz.blog.otherTest;

public class Test9PalindromeNumber {

    /**
     * 判断数字是否是回文
     * 方法一：将数字转为字符串，在判断字符串是否是回文数字
     * 方法二：之间判断数字，将number % 10 的余数链接后判断是否和源数字相等
     */
    public boolean isPalindrome(int x) {
        boolean isPalindrome = true;

        String s = x + "";
        int left = 0, right = s.length() - 1;
        while (left <= right) {
            if (s.charAt(left) != s.charAt(right)) {
                isPalindrome = false;
                break;
            }
            left++;
            right--;
        }

        return isPalindrome;
    }

    public boolean isPalindrome2(int x) {
        if (x < 0 || (x % 10 == 0 && x != 0)) {
            return false;
        }
        int pre = 0;
        while (x > pre) {
            pre = pre * 10 + x % 10;
            x /= 10;
        }

        return x == pre || x == pre / 10;
    }

    public static void main(String[] args) {
        Test9PalindromeNumber t = new Test9PalindromeNumber();
        boolean palindrome = t.isPalindrome2(12344321);
        System.out.println(palindrome);
    }
}