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…

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…

Determine whether an integer is a palindrome. Do this without extra space. 题目标签:Math 题目给了我们一个int x, 让我们判断它是不是回文数字. 首先,负数就不是回文数字,因为有个负号. 剩下的都是正数,只要把数字 reverse 一下,和原来的比较,一样就是回文. 当有overflow 的时候,返回一个负数就可以了(因为负数肯定不会和正数相等). Java Solution: Runtime beats 61.…

Long Time No See !   题目链接https://leetcode.com/problems/palindrome-number/?tab=Description   首先确定该数字的位数.按照已知数字x对10进行多次求余运算,可以得到数字位数. 具体思路: 1.每次取出该数字的最高位和最低位进行比较. 2.如果不相等则直接返回FALSE, 3.如果相等修改x的值(去掉最高位也同时去掉最低位)其中去掉最高位可以通过求模运算,去掉最低位可以采用除以10 4.进行循环直到x的值不大于…

Determine whether an integer is a palindrome. Do this without extra space.(不要使用额外的空间) 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…

/* 查看网上的思路有两种: 1.每次取两边的数,然后进行比较 2.取数的倒置数,进行比较 */ public boolean isPalindrome1(int x) { if (x<0) return false; //以四位数为例,取左边的数用的方法是/1000,取右边的数用的是%10 //注意每次取完两遍要更新数和位数 int len = 1; int temp = x; while (temp>=10) { len*=10; temp/=10; } while (x!=0) { in…

我现在在做一个叫<leetbook>的开源书项目,把解题思路都同步更新到github上了,需要的同学可以去看看 地址:https://github.com/hk029/leetcode 这个是书的地址:https://hk029.gitbooks.io/leetbook/ 009. Palindrome Number[E] 问题: Determine whether an integer is a palindrome. Do this without extra space. 思路 这里说不…

Given a non-empty string s, you may delete at most one character. Judge whether you can make it a palindrome. Example 1: Input: "aba" Output: True Example 2: Input: "abca" Output: True Explanation: You could delete the character 'c'. N…

class Solution { public: bool isPalindrome(int x) { ,init=x; ) return true; ) return false; ){ r=r*+init%; init=init/; } if(r==x) return true; else return false; } }; 题目: 判断一个整数是不是回文数,即一个数翻转过来是否跟原来的数仍一样. 需要考虑负数,负数无回文数. 解法: 翻转提供的数字,即123的话,需要翻转为321. 再判…

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…

Given a non-empty string s, you may delete at most one character. Judge whether you can make it a palindrome. Example 1: Input: "aba" Output: True Example 2: Input: "abca" Output: True Explanation: You could delete the character 'c'. N…

Valid Palindrome Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases. For example,"A man, a plan, a canal: Panama" is a palindrome."race a car" is not a palindrome. 验证回文与否,这个估计大家…

题目等级:Easy 题目描述: 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 -12…

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…

作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 目录 题目描述 题目大意 解题方法 双指针 思路来源 初版方案 进阶方案 日期 题目地址:https://leetcode.com/problems/valid-palindrome-ii/description/ 题目描述 Given a non-empty string s, you may delete at most one character. Judge whether y…

题目大意: 判断输入的数字是不是回文数.所谓回文数就是正反读都一样的数字,比如说11,121,1221这样子的数字.负数不会是回文数. 解题思路: 思路一:如果这个数是负数,则返回false,否则用一个变量记录这个数字你转后的数字,判断它和逆转前是否相等. 思路二:如果是负数或者这个数个位为0,则返回false(0除外,如果是0也返回true).否则用一个数字记录它逆转的一半,与其另一半比较,查看是否相等.(考虑数字位数的奇偶性) 解决代码: 我只写了思路二的代码,因为相对思路二的效率比思路一高…

Find the largest palindrome made from the product of two n-digit numbers. Since the result could be very large, you should return the largest palindrome mod 1337. Example: Input: 2 Output: 987 Explanation: 99 x 91 = 9009, 9009 % 1337 = 987 Note: The…

Given a string which consists of lowercase or uppercase letters, find the length of the longest palindromes that can be built with those letters. This is case sensitive, for example "Aa" is not considered a palindrome here. Note: Assume the leng…

Given a string, determine if a permutation of the string could form a palindrome. For example,"code" -> False, "aab" -> True, "carerac" -> True. 题目标签:Hash Table 题目给了我们一个string s,让我们判断它是不是可以变作回文. 看一下回文特性: 如果是偶数长度的回文,其…

Given a singly linked list, determine if it is a palindrome. Example 1: Input: 1->2 Output: false Example 2: Input: 1->2->2->1 Output: true Follow up:Could you do it in O(n) time and O(1) space? 这道题让我们判断一个链表是否为回文链表,LeetCode 中关于回文串的题共有六道,除了这道,其…

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…

题目 Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward. Example1:   Input:121   Output:true Example2:   Input:-121   Output:flase   Explanation:From left to right, it reads -121. From ri…

Given a string s, return all the palindromic permutations (without duplicates) of it. Return an empty list if no palindromic permutation could be form. For example: Given s = "aabb", return ["abba", "baab"]. Given s = "a…

给定一个非空字符串 s,最多删除一个字符.判断是否能成为回文字符串. 示例 1: 输入: "aba" 输出: True 示例 2: 输入: "abca" 输出: True 解释: 你可以删除c字符. 注意: 字符串只包含从 a-z 的小写字母.字符串的最大长度是50000. class Solution { public: bool validPalindrome(string s) { int len = s.size(); if(len == 0) return…

Given a non-empty string s, you may delete at most one character. Judge whether you can make it a palindrome. Example 1: Input: "aba" Output: True Example 2: Input: "abca" Output: True Explanation: You could delete the character 'c'. N…

Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases. For example,"A man, a plan, a canal: Panama" is a palindrome."race a car" is not a palindrome. Note:Have you consider that th…

将int转换为string,注意for循环判断条件的简化 class Solution { public: bool isPalindrome(int x) { ) return false; string s = to_string(x); int si = s.size(); ; i<si/;i++) { )) { return false; } } return true; } };…

Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases. For example,"A man, a plan, a canal: Panama" is a palindrome."race a car" is not a palindrome. Note:Have you consider that th…

Given a string which consists of lowercase or uppercase letters, find the length of the longest palindromes that can be built with those letters. This is case sensitive, for example "Aa" is not considered a palindrome here. Note:Assume the lengt…

Easy! 题目描述: 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? 判断一个整数是否是回文数.不能使用辅助空间…