文章--LeetCode算法--TwoSumPalindromeNumbe

目录

• PalindromeNumber
  • 问题描述
  • 实例
  • 实现代码

PalindromeNumber

问题描述

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

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.

实例

• Example 1:

Input: 121

Output: true

• Example 2:

Input: -121

Output: false

Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome.

• Example 3:

Input: 10

Output: false

Explanation: Reads 01 from right to left. Therefore it is not a palindrome.

实现代码

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