题目:给定一个罗马数字串,转换为一个整数. 一开始没理解,以为是string to int.后来理解:罗马数字与阿拉伯数字的映射关系,见下图: 至此,题目的意思才掌握明白,用程序模拟这张表. 无可置否,需要将这张表的映射关系存进一个map中,对输入的string查找map中的映射关系. 先贴上代码:(注:substring(startIndex,endIndex) 截取的子字符串是从startIndex处到endIndex-1处为止的) public int romanToInt(String…

[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…

Given a roman numeral, convert it to an integer. Input is guaranteed to be within the range from 1 to 3999. 罗马数转化成数字问题,我们需要对于罗马数字很熟悉才能完成转换.以下截自百度百科: 罗马数字是最早的数字表示方式,比阿拉伯数字早2000多年,起源于罗马. 如今我们最常见的罗马数字就是钟表的表盘符号:Ⅰ,Ⅱ,Ⅲ,Ⅳ(IIII),Ⅴ,Ⅵ,Ⅶ,Ⅷ,Ⅸ,Ⅹ,Ⅺ,Ⅻ…… 对应阿拉伯数字(就是现…

Implement atoi to convert a string to an integer. Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below and ask yourself what are the possible input cases. Notes: It is intended for this problem to be spe…

题目来源:https://leetcode.com/problems/reverse-integer/ Reverse digits of an integer. Example1: x = 123, return 321Example2: x = -123, return -321 解题思路: 其实这道题看起来非常简单,要实现也是几行代码的事.但是有个小问题容易被忽略,就是边界问题.什么意思呢?如果我们输入的整数超出了int的表达范围,这个问题要怎么解决呢? 用比int更大的数据类型存储我们转…

Question: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…

# -*- coding: utf8 -*-'''__author__ = 'dabay.wang@gmail.com'https://oj.leetcode.com/problems/reverse-integer/ Reverse digits of an integer. Example1: x = 123, return 321Example2: x = -123, return -321 Have you thought about this?Here are some good qu…

一天一道LeetCode系列 (一)题目 Given an integer, convert it to a roman numeral. Input is guaranteed to be within the range from 1 to 3999. (二)解题 将整形数字转换成罗马数字 罗马数字共有七个,即I(1),V(5),X(10),L(50),C(100),D(500),M(1000) 举例:Ⅰ.Ⅱ.Ⅲ.Ⅳ.Ⅴ.Ⅵ.Ⅶ.Ⅷ.Ⅸ.Ⅹ.Ⅺ.Ⅻ表示1-11 代码: class Solut…

String to Integer (atoi) Implement atoi to convert a string to an integer. Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below and ask yourself what are the possible input cases. Notes: It is intended f…

最近在LeetCode上做题,写点东西记录一下,虽然自己做的都是些很水的题目,但是重在练手. 题号7:Reverse Integer,题目描述: Reverse digits of an integer:例如,输入123,输出321:输入-123,输出-321. 思路很简单:将原数的每一位求出,然后将原数的每一位倒序,生成一个整数.在程序中,使用了队列,利用其先进先出的原则,倒序原数每一位. 注意的地方:防止溢出. 代码如下: class Solution { public: int rever…