题目链接: http://poj.org/problem?id=2402 题目大意就是让你找到第n个回文数是什么. 第一个思路当然是一个一个地构造回文数直到找到第n个回文数为止(也许大部分人一开始都是这样的思路). 很明显找到第n个之前的所有操作都是浪费, 这也是这个方法的最大弱点. 抱着侥幸心理(谁知道数据弱不弱啊)用这种方法提交了下, TLE (在另一个OJ上提交是9个测试点过了6个). 第二个思路也很容易想到, 但是比第一个思路要麻烦: 第n个回文数的每位数字都与n有一定的关联. 也就是说…

A palindrome is a word, number, or phrase that reads the same forwards as backwards. For example, the name “anna” is a palindrome. Numbers can also be palindromes (e.g. 151 or 753357). Additionally numbers can of course be ordered in size. The first…

Determine whether an integer is a palindrome. Do this without extra space. click to show spoilers. Some hints: Could negative integers be palindromes? (ie, -1) If you are thinking of converting the integer to string, note the restriction of using ext…

Problem: Determine whether an integer is a palindrome. Do this without extra space. 简单的回文数,大一肯定有要求写过,不过从基础开始尝试吧. Solution: public class Solution { public boolean isPalindrome(int x) { int n=1; int copyx=x; if(x<0)return false; if(x<10)return true; w…

Find the smallest prime palindrome greater than or equal to N. Recall that a number is prime if it's only divisors are 1 and itself, and it is greater than 1.  For example, 2,3,5,7,11 and 13 are primes. Recall that a number is a palindrome if it read…

描述: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 a…

Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward. Example 1: Input: 121 Output: true Example 2: Input: -121 Output: false Explanation: From left to right, it reads -121. From right to…

作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 公众号:负雪明烛 本文关键词:回文数,回文,题解,Leetcode, 力扣,Python, C++, Java 目录 题目描述 题目大意 解题方法 判断回文字符串 翻转数字 日期 题目地址:https://leetcode.com/problems/palindrome-number/#/description 题目描述 Determine whether an integer is…

判断一个数字是否是回文数,尝试不用其他额外空间. 注意: 负数也有可能成为回文数吗? 如果你想让int转为string,注意不用其他空间这个约束. 你也可以翻转一个int,但是有可能会溢出.     public class Solution { public boolean isPalindrome(int x) { if(x<0) return false; int temp = x, reverseX = 0; while (temp > 0) { reverseX = reverseX…

这道题是LeetCode里的第9道题. 题目说的: 判断一个整数是否是回文数.回文数是指正序(从左向右)和倒序(从右向左)读都是一样的整数. 示例 1: 输入: 121 输出: true 示例 2: 输入: -121 输出: false 解释: 从左向右读, 为 -121 . 从右向左读, 为 121- .因此它不是一个回文数. 示例 3: 输入: 10 输出: false 解释: 从右向左读, 为 01 .因此它不是一个回文数. 进阶: 你能不将整数转为字符串来解决这个问题吗? 这道题虽然简单…