Roman to Integer Given a roman numeral, convert it to an integer. Input is guaranteed to be within the range from 1 to 3999. 解法一:非递归 从左到右遍历每个字符,并记录上个字符来处理双字符情况即可. class Solution { public: int romanToInt(string s) { ; ; ; i < s.size(); i ++) { switch(…

题目: Given a roman numeral, convert it to an integer. Input is guaranteed to be within the range from 1 to 3999. 思路:与12题正好相反,罗马数字基本字符集:I V X L C D M (1, 5, 10, 50, 100, 500, 1000).思路是从字符串最低位开始匹配,累加相应字符对应的阿拉伯数字,要注意的就是I,X,L(1,10,100)要判断是在左还是在右,在左就减在右就加.…

题目描述: Given a roman numeral, convert it to an integer. 解题分析: 这道题只要百度一下转换的规则,然后着这解释写代码即可.实现上并没有什么难度,直接看代码即可 具体代码: public class Solution { public int romanToInt(String s){ int[] value={1000,500,100,50,10,5,1}; char[] array ="MDCLXVI".toCharArray()…

一天一道LeetCode系列 (一)题目 Given a roman numeral, convert it to an integer. Input is guaranteed to be within the range from 1 to 3999. (二)解题 和上一题相反,这题将罗马数字转换成整形数. 注意到 4,9,40,90,400,900这些特殊的数字的区别就不难写出代码了. class Solution { public: int romanToInt(string s) {…

Given a roman numeral, convert it to an integer. Input is guaranteed to be within the range from 1 to 3999. 题解: 只要知道罗马数字的规律即可 基本字符 I V X L C D M 相应的阿拉伯数字表示为 1 5 10 50 100 500 1000   1.相同的数字连写,所表示的数等于这些数字相加得到的数,如:Ⅲ = 3: 2.小的数字在大的数字的右边,所表示的数等于这些数字相加得到的…

13.Roman to Integer Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M. Symbol Value I 1 V 5 X 10 L 50 C 100 D 500 M 1000 For example, two is written as II in Roman numeral, just two one's added together. Twelve is writ…

我现在在做一个叫<leetbook>的免费开源书项目,力求提供最易懂的中文思路,目前把解题思路都同步更新到gitbook上了,需要的同学可以去看看 书的地址:https://hk029.gitbooks.io/leetbook/ 013. Roman to Integer 问题 Given a roman numeral, convert it to an integer. Input is guaranteed to be within the range from 1 to 3999. S…

#-*- coding: UTF-8 -*-#从前向后遍历罗马数字,#如果某个数比前一个数小,则加上该数.反之,减去前一个数的两倍然后加上该数###-----技术规则-----#-------------------------------------------------------------------------------------##1.相同的数字连写,所表示的数等于这些数字相加得到的数,例如:III = 3##2.小的数字在大的数字右边,所表示的数等于这些数字相加得到的数,例如…

https://leetcode.com/problems/roman-to-integer/ 原题: Given a roman numeral, convert it to an integer. Input is guaranteed to be within the range from 1 to 3999. 思路: 关键是要搞清罗马数字规则.PS:不用考虑错误输入. 核心: 遍历一遍,相同字母合并成对应数,然后比较如果比它后面的小就减去,否则就加上.时间复杂度O(n). 具体解析: 基…

题目等级:Easy 题目描述: Given a 32-bit signed integer, reverse digits of an integer. Example 1: Input: 123 Output: 321 Example 2: Input: -123 Output: -321 Example 3: Input: 120 Output: 21    题意: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. 解题思路:   本题很简单,我们给出以下两种方法.  …

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:字符串转整数,atoi,题解,Leetcode, 力扣,Python, C++, Java 目录 题目描述 题目大意 解题方法 代码 日期 题目地址:https://leetcode-cn.com/problems/string-to-integer-atoi/ 题目描述 Implement the myAtoi(string s) function, w…

题目: 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…

7 - Reverse digits of an integer. Example1: x = 123, return 321Example2: x = -123, return -321 Notice: 1.If the integer's last digit is 0, what should the output be? ie, cases such as 10, 100. 2.Did you notice that the reversed integer might overflow…

题目描述: 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…

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…

题目如下: Given a function  f(x, y) and a value z, return all positive integer pairs x and y where f(x,y) == z. The function is constantly increasing, i.e.: f(x, y) < f(x + 1, y) f(x, y) < f(x, y + 1) The function interface is defined like this: interfa…

题目 罗马数字包含以下七种字符: I, V, X, L,C,D 和 M. 字符 数值 I 1 V 5 X 10 L 50 C 100 D 500 M 1000 例如, 罗马数字 2 写做 II ,即为两个并列的 1.12 写做 XII ,即为 X + II . 27 写做  XXVII, 即为 XX + V + II .通常情况下,罗马数字中小的数字在大的数字的右边.但也存在特例,例如 4 不写做 IIII,而是 IV.数字 1 在数字 5 的左边,所表示的数等于大数 5 减小数 1 得到的数值…

分析 把具体的情况一个一个实现即可,没有什么幺蛾子. 代码 class Solution { public int romanToInt(String s) { int ans = 0; for (int i=0; i!=s.length(); ++i) { switch(s.charAt(i)) { case 'I': if(i<s.length()-1 && (s.charAt(i+1)=='X' || s.charAt(i+1)=='V')) { ans--; break; }…

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…

12 - Integer to Roman Given an integer, convert it to a roman numeral. Input is guaranteed to be within the range from 1 to 3999. Solution: 枚举,考虑每个字符以及每两个字符的组合 1 class Solution { 2 public: 3 string intToRoman(int num) { //runtime:28ms 4 string ret; 5…

[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…

题目描述 罗马数字包含以下七种字符:I, V, X, L,C,D 和 M. 字符 数值 I 1 V 5 X 10 L 50 C 100 D 500 M 1000 例如, 罗马数字 2 写做 II ,即为两个并列的 1.12 写做 XII ,即为 X + II . 27 写做 XXVII, 即为 XX + V + II . 通常情况下,罗马数字中小的数字在大的数字的右边.但也存在特例,例如 4 不写做 IIII,而是 IV.数字 1 在数字 5 的左边,所表示的数等于大数 5 减小数 1 得到的数…

13. Roman to Integer Easy Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M. Symbol Value I 1 V 5 X 10 L 50 C 100 D 500 M 1000 For example, two is written as II in Roman numeral, just two one's added together. Twelve i…

1.题目13. Roman to Integer Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M. Symbol Value I 1 V 5 X 10 L 50 C 100 D 500 M 1000 For example, two is written as II in Roman numeral, just two one's added together. Twelve is…

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 BFS 日期 题目地址:https://leetcode-cn.com/problems/ji-qi-ren-de-yun-dong-fan-wei-lcof/ 题目描述 地上有一个m行n列的方格,从坐标 [0,0] 到坐标 [m-1,n-1] .一个机器人从坐标 [0, 0] 的格子开始移动,它每次可以向左.右.上.下移动一格(不能移动到方格外),也…

[LeetCode]386. Lexicographical Numbers 解题报告(Python) 标签(空格分隔): LeetCode 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.me/ 题目地址:https://leetcode.com/problems/lexicographical-numbers/description/ 题目描述: Given an integer n, return 1 - n in lexicogra…

[LeetCode]402. Remove K Digits 解题报告(Python) 标签(空格分隔): LeetCode 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 题目地址:https://leetcode.com/problems/remove-k-digits/description/ 题目描述: Given a non-negative integer num represented as a string, rem…

[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…

[LeetCode]385. Mini Parser 解题报告(Python) 标签: LeetCode 题目地址:https://leetcode.com/problems/mini-parser/description/ 题目描述: Given a nested list of integers represented as a string, implement a parser to deserialize it. Each element is either an integer, o…

[LeetCode]331. Verify Preorder Serialization of a Binary Tree 解题报告(Python) 标签: LeetCode 题目地址:https://leetcode.com/problems/verify-preorder-serialization-of-a-binary-tree/description/ 题目描述: One way to serialize a binary tree is to use pre-order traver…