这道题是LeetCode里的第7道题. 题目描述: 给出一个 32 位的有符号整数,你需要将这个整数中每位上的数字进行反转. 示例 1: 输入: 123 输出: 321  示例 2: 输入: -123 输出: -321 示例 3: 输入: 120 输出: 21 注意: 假设我们的环境只能存储得下 32 位的有符号整数,则其数值范围为 [−231,  231 − 1].请根据这个假设,如果反转后整数溢出那么就返回 0. 首先,这是一道简单题,根据我多年的做题经验来看,这道题肯定有坑,绝对会有 IN…

Reverse digits of an integer. Example1: x = 123, return 321Example2: x = -123, return -321 总结:处理整数溢出的方法 ①用数据类型转换long  或 long long ②在每次循环时先保存下数字变化之前的值,处理后单步恢复看是否相等 (比③好) ③整体恢复,看数字是否相等. 思路:注意30000这样以0结尾的数字,注意越界时返回0. 我检查越界是通过把翻转的数字再翻转回去,看是否相等. int rever…

题目描述: Reverse digits of an integer. Example1: x = 123, return 321Example2: x = -123, return -321 很简单的题目其实用个数组就能解决了,不过用了一下queue,注意负数的情况. class Solution { public: int reverse(int x) { bool flg=false; ){ flg=true; x=-x; } queue<int> a; ){ a.push(x%); x…

[LeetCode]397. Integer Replacement 解题报告(Python) 标签: LeetCode 题目地址:https://leetcode.com/problems/integer-replacement/description/ 题目描述: Given a positive integer n and you can do operations as follow: If n is even, replace n with n/2. If n is odd, you…

六月箴言 万物之中,希望最美:最美之物,永不凋零.—— 斯蒂芬·金 第二周算法记录 007 -- Reverse Integer (整数反转) 题干英文版: Given a 32-bit signed integer, reverse digits of an integer. Example 1: Input: 123Output: 321 Example 2: Input: -123Output: -321 Example 3: Input: 120Output: 21 Note:Assum…

Reverse digits of an integer. Example1: x = 123, return 321Example2: x = -123, return -321 Have you thought about this? Here are some good questions to ask before coding. Bonus points for you if you have already thought through this! If the integer's…

Reverse digits of an integer. Example1: x = 123, return 321Example2: x = -123, return -321 Have you thought about this? Here are some good questions to ask before coding. Bonus points for you if you have already thought through this! If the integer's…

Reverse bits of a given 32 bits unsigned integer. For example, given input 43261596 (represented in binary as 00000010100101000001111010011100), return 964176192 (represented in binary as00111001011110000010100101000000). 思路: n一直右移, ans一直左移. class So…

今天第一次在leetcode上提交了一个题目,据说这个网站基本上都是名企面试笔试题,今天无意一进去就看到第一题居然就是昨天的腾讯实习生笔试题,赶紧注册了个账号做题. 题目描述: Given an input string, reverse the string word by word. For example,Given s = "the sky is blue",return "blue is sky the".   很简单的英文就不翻译了.题目不难但是做这个题…

题目描述: 解题思路: 反转的方法很简单,重点在于判断溢出的问题,下面给出了两种方法. Java代码: 方法一: 判断溢出方法:在执行完int newResult=result*10+tail语句后,紧接着进行逆运算result=(newResult-tail)/10,如果出现溢出,那么逆运算后result和newResult必然不相等,反之,如果没有溢出,则逆运算后result=newResult. public class LeetCode7 { public static void mai…

思路:取绝对值,反转,并判断反转的结果是否大于最大整数,需要注意的细节:判断时需要这样:result > (Integer.MAX_VALUE - v) / 10 否则result * 10 + v% 10 > Integer.MAX_VALUE左边会直接出现溢出.最后加上符号位. public int reverse(int x) { if(x==Integer.MIN_VALUE){ return 0; } //然后取绝对值,判断绝对值不大于Integer.MAX_VALUDE,不能直接用…

一年没有管理博客园了,说来实在惭愧.. 最近开始刷LeetCode,之前没刷过,说来也实在惭愧... 刚开始按 AC Rates 从简单到难刷,觉得略无聊,就决定按 Add Date 刷,以后也可能看心情随便选题…(⊙o⊙)…今天做了14年 Add 的三个题,其中 Maximum Product Subarray 着实把我折腾了好一会儿,所以想想还是跟大家分享一下我的解法,也或许有更好的方法,期待大家的分享.就把三个题按 Add Date 的先后顺序分享一下吧. Add Date 2014-03…

这是LeetCode里的第25道题. 题目要求: 给出一个链表,每 k 个节点一组进行翻转,并返回翻转后的链表. k 是一个正整数,它的值小于或等于链表的长度.如果节点总数不是 k 的整数倍,那么将最后剩余节点保持原有顺序. 示例 : 给定这个链表:1->2->3->4->5 当 k = 2 时,应当返回: 2->1->4->3->5 当 k = 3 时,应当返回: 3->2->1->4->5 说明 : 你的算法只能使用常数的额外空间…

作者: 负雪明烛 id: fuxuemingzhu 个人博客:http://fuxuemingzhu.cn/ 个人公众号:负雪明烛 本文关键词:roman, 罗马数字,题解,leetcode, 力扣,Python, C++, Java 目录 题目描述 题目大意 解题方法 日期 题目描述 Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M. Symbol Value I 1 V 5 X…

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 数学解法 动态规划 日期 题目地址:https://leetcode.com/problems/integer-break/description/ 题目描述 Given a positive integer n, break it into the sum of at least two positive integers and maximize…

Reverse Nodes in k-Group Given a linked list, reverse the nodes of a linked list k at a time and return its modified list. If the number of nodes is not a multiple of k then left-out nodes in the end should remain as it is. You may not alter the valu…

Reverse Linked List II Reverse a linked list from position m to n. Do it in-place and in one-pass. For example:Given 1->2->3->4->5->NULL, m = 2 and n = 4, return 1->4->3->2->5->NULL. Note:Given m, n satisfy the following cond…

Given a linked list, reverse the nodes of a linked list k at a time and return its modified list. If the number of nodes is not a multiple of k then left-out nodes in the end should remain as it is. You may not alter the values in the nodes, only nod…

Reverse a linked list from position m to n. Do it in-place and in one-pass. For example:Given 1->2->3->4->5->NULL, m = 2 and n = 4, return 1->4->3->2->5->NULL. 思路: 好困啊,脑子晕晕的. 转了半天AC了.但写的很罗嗦,要学习大神的写法. 注意翻转的写法. 用伪头部 大神14行简洁代码 L…

Reverse a singly linked list. 思路:没啥好说的.秒... ListNode* reverseList(ListNode* head) { ListNode * rList = NULL, * tmp = NULL; while(head != NULL) { tmp = rList; rList = head; head = head->next; rList->next = tmp; } return rList; }…

Given an input string, reverse the string word by word. For example,Given s = "the sky is blue",return "blue is sky the". For C programmers: Try to solve it in-place in O(1) space. Clarification: What constitutes a word?A sequence of n…

Integer to English Words Convert a non-negative integer to its english words representation. Given input is guaranteed to be less than 231 - 1. For example, 123 -> "One Hundred Twenty Three" 12345 -> "Twelve Thousand Three Hundred For…

题目: Given an integer, convert it to a roman numeral. Input is guaranteed to be within the range from 1 to 3999. 思路: 主要是了解罗马数和阿拉伯数字的对应关系,如下表: 由这个表基本上可以将1-3999范围的阿拉伯数字换成罗马数字.在处理阿拉伯数字时从高位开始匹配,将每个位的值找出对应罗马数字,串成字符串即可. public class Solution { public String…

题目描述: Given an integer, convert it to a roman numeral. Input is guaranteed to be within the range from 1 to 3999. 解题思路: 注意到用例比较少,所以采用以空间换时间的方法,把所有的结果列出,然后组合出输入值n的字符串即可. 具体代码: public class Solution { public static String intToRoman(int num) { String[]…

Integer to Roman Given an integer, convert it to a roman numeral. Input is guaranteed to be within the range from 1 to 3999. 逐区间做处理. 解法一:非递归 class Solution { public: string intToRoman(int num) { string ret; //M<-->1000 ) { ret += 'M'; num -= ; } //t…

Given an integer, convert it to a roman numeral. Input is guaranteed to be within the range from 1 to 3999. 题解: 观察 1 到 10 :Ⅰ,Ⅱ,Ⅲ,Ⅳ(IIII),Ⅴ,Ⅵ,Ⅶ,Ⅷ,Ⅸ,Ⅹ,Ⅺ 难点在于出现字符不能连续超过三次,以及大数左边至多有一个小数.所以要分情况:1 - 3,4,5 - 8,9.将小数在大数左边的情况摘出来. Solution 1 贪心策略 class Solutio…

[2]Add Two Numbers (2018年12月23日,review) 链表的高精度加法. 题解:链表专题:https://www.cnblogs.com/zhangwanying/p/9797184.html [7]Reverse Integer (2018年12月23日, review) 给了一个32位的整数,返回它的reverse后的整数.如果reverse后的数超过了整数的范围,就返回 0. Example 1: Input: 123 Output: 321 Example 2:…

[Question] Reverse digits of an integer. Example: x = 123, return 321 x = -123, return -321 [My Solution] class Solution(object): def reverse(self, x): """ :type x: int :rtype: int """ neg = 1 if x < 0: neg = -1 if x == 0:…

[LeetCode]150. Evaluate Reverse Polish Notation 解题报告(Python) 标签: LeetCode 题目地址:https://leetcode.com/problems/evaluate-reverse-polish-notation/description/ 题目描述: Evaluate the value of an arithmetic expression in Reverse Polish Notation. Valid operator…

Algorithm [leetcode]557. Reverse Words in a String III https://leetcode.com/problems/reverse-words-in-a-string-iii/ 1)problem Given a string, you need to reverse the order of characters in each word within a sentence while still preserving whitespace…