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…

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…

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…

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[]…

12. 整数转罗马数字 知识点:字符串 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,…

[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…

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…

写在前面   老粉丝可能知道现阶段的LeetCode刷题将按照某一个特定的专题进行,之前的[贪心算法]已经结束,虽然只有三个题却包含了简单,中等,困难这三个维度,今天介绍的是第二个专题[数组] 数组(Array)是一种线性表数据结构.它用一组连续的内存空间,来存储一组具有相同类型的数据.在每一种编程语言中,基本都会有数组这种数据类型.不过,它不仅仅是一种编程语言中的数据类型,还是一种最基础的数据结构. 贪心算法回顾: [LeetCode]贪心算法--买卖股票的最佳时机II(122) [LeetC…

[LeetCode]760. Find Anagram Mappings 解题报告 标签(空格分隔): LeetCode 题目地址:https://leetcode.com/problems/find-anagram-mappings/description/ 题目描述: Given two lists Aand B, and B is an anagram of A. B is an anagram of A means B is made by randomizing the order o…

[LeetCode]870. Advantage Shuffle 解题报告(Python) 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 题目地址:https://leetcode.com/problems/advantage-shuffle/description/ 题目描述: Given two arrays A and B of equal size, the advantage of A with respect to B…

[LeetCode]129. Sum Root to Leaf Numbers 解题报告(Python) 标签(空格分隔): LeetCode 题目地址:https://leetcode.com/problems/sum-root-to-leaf-numbers/description/ 题目描述: Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a numbe…

[LeetCode]556. Next Greater Element III 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/next-greater-element-iii/description/ 题目描述: Given a positive 32-bit integer n, you need…

[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]378. Kth Smallest Element in a Sorted Matrix 解题报告(Python) 标签: LeetCode 题目地址:https://leetcode.com/problems/kth-smallest-element-in-a-sorted-matrix/description/ 题目描述: Given a n x n matrix where each of the rows and columns are sorted in ascen…

[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…

[LeetCode]831. Masking Personal Information 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/masking-personal-information/description/ 题目描述: We are given a personal information…

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 日期 题目地址:https://leetcode.com/problems/linked-list-components/description/ 题目描述 We are given head, the head node of a linked list containing unique integer values. We are also g…

[LeetCode]Minimum Depth of Binary Tree Given a binary tree, find its minimum depth. The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node. 递归和非递归,此提比较简单.广度优先遍历即可.关键之处就在于如何保持访问深度. 下面是4种代码: im…

53. Maximum Subarray[leetcode] Find the contiguous subarray within an array (containing at least one number) which has the largest sum. For example, given the array [-2,1,-3,4,-1,2,1,-5,4],the contiguous subarray [4,-1,2,1] has the largest sum = 6. 挑…

[刷题][LeetCode]总 用动画的形式呈现解LeetCode题目的思路 参考链接-空 007-整数反转 方法: 弹出和推入数字 & 溢出前进行检查 思路: 我们可以一次构建反转整数的一位数字.在这样做的时候,我们可以预先检查向原整数附加另一位数字是否会导致溢出. 算法: 反转整数的方法可以与反转字符串进行类比. 我们想重复"弹出" x 的最后一位数字,并将它"推入"到 rev 的后面.最后,rev 将与 x 相反. 要在没有辅助堆栈 / 数组的帮助下…

全排列问题.经常使用的排列生成算法有序数法.字典序法.换位法(Johnson(Johnson-Trotter).轮转法以及Shift cursor cursor* (Gao & Wang)法. [题目] Given a collection of numbers, return all possible permutations. For example, [1,2,3] have the following permutations: [1,2,3], [1,3,2], [2,1,3], [2…

[题目] Given a collection of numbers that might contain duplicates, return all possible unique permutations. For example, [1,1,2] have the following unique permutations: [1,1,2], [1,2,1], and [2,1,1]. [解析] 题意:求一个数组的全排列.与[LeetCode]Permutations 解题报告 不同的是…

[LeetCode]First Missing Positive Given an unsorted integer array, find the first missing positive integer. For example, Given [1,2,0] return 3, and [3,4,-1,1] return 2. Your algorithm should run in O(n) time and uses constant space. 找到第一个没有出现的正整数 思路:…

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…

使用最小花费爬楼梯 数组的每个索引做为一个阶梯,第 i个阶梯对应着一个非负数的体力花费值 cost[i](索引从0开始). 每当你爬上一个阶梯你都要花费对应的体力花费值,然后你可以选择继续爬一个阶梯或者爬两个阶梯. 您需要找到达到楼层顶部的最低花费.在开始时,你可以选择从索引为 0 或 1 的元素作为初始阶梯. 示例 1: 输入: cost = [10, 15, 20] 输出: 15 解释: 最低花费是从cost[1]开始,然后走两步即可到阶梯顶,一共花费15. 示例 2: 输入: cost =…

题目如下: An integer has sequential digits if and only if each digit in the number is one more than the previous digit. Return a sorted list of all the integers in the range [low, high] inclusive that have sequential digits. Example 1: Input: low = 100,…