题意:有一个整数序列,从中挑出一些数字,使得总和是最大,前提是,相邻的两个数字中只能挑其一.比如1 2 3 就只能挑2或者1和3. 思路:很直观的题,dp思想.降低规模,从小规模开始考虑.如果只有两个数字,那么结果很明显就能知道是其中之大者.假如已经知道了第 i 个之前的决策,那么第i+2个之前的决策也就知道了.前两个数字已经由人工得知,设为dp[0]和dp[1],那么dp[2]=max(dp[0]+nums[2], dp[1]).状态转移方程dp[i]=max(dp[i-1], dp[i-2]…

213. House Robber II     Total Accepted: 24216 Total Submissions: 80632 Difficulty: Medium Note: This is an extension of House Robber. After robbing those houses on that street, the thief has found himself a new place for his thievery so that he will…

Note: This is an extension of House Robber. After robbing those houses on that street, the thief has found himself a new place for his thievery so that he will not get too much attention. This time, all houses at this place are arranged in a circle.…

You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from robbing each of them is that adjacent houses have security system connected and it will autom…

原题链接在这里:https://leetcode.com/problems/house-robber-iii/ 题目: The thief has found himself a new place for his thievery again. There is only one entrance to this area, called the "root." Besides the root, each house has one and only one parent hous…

原题链接在这里:https://leetcode.com/problems/house-robber/ 题目: You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from robbing each of them is that adjacent…

The thief has found himself a new place for his thievery again. There is only one entrance to this area, called the "root." Besides the root, each house has one and only one parent house. After a tour, the smart thief realized that "all hou…

本题和House Robber差不多,分成两种情况来解决.第一家是不是偷了,如果偷了,那么最后一家肯定不能偷. class Solution(object): def rob(self, nums): """ :type nums: List[int] :rtype: int """ if not nums: return 0 n = len(nums) if n == 1: return nums[0] if n == 2: return ma…

Description: You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from robbing each of them is that adjacent houses have security system connected and…

Leetcode 466 直接给出DP方程 dp[i][k]=dp[i][k-1]+dp[(i+dp[i][k-1])%len1][k-1]; dp[i][k]表示从字符串s1的第i位开始匹配2^k个s2串需要的长度 最后通过一个循环 累积最多可以匹配多少个s2串 除以n2下取整就是答案 用倍增加速后 总的复杂度nlogn 而本题的n非常小 轻松AC 体会到倍增的魅力了吧. const int maxn=100+1,INF=1e+9; long long int dp[maxn][30]; cl…

题目 给出 n 代表生成括号的对数,请你写出一个函数,使其能够生成所有可能的并且有效的括号组合. 例如,给出 n = 3,生成结果为: [ "((()))", "(()())", "(())()", "()(())", "()()()" ] 来源:力扣(LeetCode) 链接:https://leetcode-cn.com/problems/generate-parentheses 著作权归领扣网络所有.…

题目 给定 n 个非负整数表示每个宽度为 1 的柱子的高度图,计算按此排列的柱子,下雨之后能接多少雨水. 上面是由数组 [0,1,0,2,1,0,1,3,2,1,2,1] 表示的高度图,在这种情况下,可以接 6 个单位的雨水(蓝色部分表示雨水). 感谢 Marcos 贡献此图. 示例: 输入: [0,1,0,2,1,0,1,3,2,1,2,1] 输出: 6 来源:力扣(LeetCode) 链接:https://leetcode-cn.com/problems/trapping-rain-wate…

题意: 给一个n*m的矩阵,每次可以往下或右走,经过的格子中的数字之和就是答案了,答案最小为多少? 思路: 比较水,只是各种空间利用率而已. 如果可以在原空间上作修改. class Solution { public: int minPathSum(vector<vector<int>>& grid) { ; ; ; j<=m; j++) grid[][j]+=grid[][j-]; ; i<=n; i++) { grid[i][]+=grid[i-][]; ;…

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/ 010. Regular Expression Matching 问题 Implement regular expression matching with support for ‘.’ and ‘*’. ‘.’ Matches any single charact…

837. 新21点 爱丽丝参与一个大致基于纸牌游戏 "21点" 规则的游戏,描述如下: 爱丽丝以 0 分开始,并在她的得分少于 K 分时抽取数字. 抽取时,她从 [1, W] 的范围中随机获得一个整数作为分数进行累计,其中 W 是整数. 每次抽取都是独立的,其结果具有相同的概率. 当爱丽丝获得不少于 K 分时,她就停止抽取数字. 爱丽丝的分数不超过 N 的概率是多少? 示例 1: 输入:N = 10, K = 1, W = 10 输出:1.00000 说明:爱丽丝得到一张卡,然后停止.…

题意: 一棵BST有n个节点,每个节点的key刚好为1-n.问此树有多少种不同形态? 思路: 提示是动态规划. 考虑一颗有n个节点的BST和有n-1个节点的BST.从n-1到n只是增加了一个点n,那么点n可以放的地方并不多,而且有一些规律.由于n是最大的,所以必定是在最右边,但是它的上面和下面也可以有一些点,假设点n的上面有k个点,下面则为n-k-1个.观察到点n的上面的点必定是[1, n-k-1],下面的点是[n-k, n-1],而点数<n的BST的形态数都已经求出,那么枚举这个k值就行了.…

leetcode403 我们维护青蛙从某个石头上可以跳那些长度的距离即可 用平衡树维护. 总的复杂度O(n^2logn) class Solution { public: bool canCross(vector<int>& stones) { map<int,int>po; int n=stones.size(); map<int,int>dis[1500]; for(int i=0;i<stones.size();i++) po[stones[i]]=…

参考https://oj.leetcode.com/problems/distinct-subsequences 动态规划方程 dp[i][j]=dp[i-1][j-1]+dp[i-1][j] (s(i)==t(i)) dp[i][j]=dp[i-1][j]; 边界条件:  iif(j==0) d[i][j]=1; 自己画个矩阵看看. 可能出错, 1.直接递归超时 public class Solution { public int numDistinct(String S, String T)…

House Robber:不能相邻,求能获得的最大值 House Robber II:不能相邻且第一个和最后一个不能同时取,求能获得的最大值 House Robber III:二叉树下的不能相邻,求能获得的最大值 Paint House:用3种颜色,相邻的房屋不能用同一种颜色,求花费最小 Paint House II:用k种颜色,相邻的房屋不能用同一种颜色,求花费最小Paint Fence:用k种颜色,相邻的可以用同一种颜色,但不能超过连续的2个,求有多少种可能性 198. House Robb…

463. Island Perimeterhttps://leetcode.com/problems/island-perimeter/就是逐一遍历所有的cell,用分离的cell总的的边数减去重叠的边的数目即可.在查找重叠的边的数目的时候有一点小技巧,就是沿着其中两个方向就好,这种题目都有类似的规律,就是可以沿着上三角或者下三角形的方向来做.一刷一次ac,但是还没开始注意codestyle的问题,需要再刷一遍. class Solution { public: int islandPerime…

Here is my collection of solutions to leetcode problems. Related code can be found in this repo: https://github.com/zhuli19901106/leetcode LeetCode - Course Schedule LeetCode - Reverse Linked List LeetCode - Isomorphic Strings LeetCode - Count Primes…

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/delete-operation-for-two-strings/description/ 题目描述 Given two words word1 and word2, find the minimum number of steps required to make word…

题目: A robot is located at the top-left corner of a m x ngrid (marked 'Start' in the diagram below). The robot can only move either down or right at any point in time. The robot is trying to reach the bottom-right corner of the grid (marked 'Finish' i…

Java Algorithm Problems 程序员的一天 从开始这个Github已经有将近两年时间, 很高兴这个repo可以帮到有需要的人. 我一直认为, 知识本身是无价的, 因此每逢闲暇, 我就会来维护这个repo, 给刷题的朋友们一些我的想法和见解. 下面来简单介绍一下这个repo: README.md: 所有所做过的题目 ReviewPage.md: 所有题目的总结和归纳(不断完善中) KnowledgeHash2.md: 对所做过的知识点的一些笔记 SystemDesign.md:…

代码自己去LOJ看 JOI2013 彩灯 把序列划分成若干极长交替列,那么最优的方案一定是将一个极长交替列翻转使得连续的三个极长交替列合成一个.计算相邻三个极长交替列长度的最大值即可. 搭乘IOI火车 DP:\(f_{i,j}\)表示两个串的起点分别在\(i,j\)位置最长的拼接长度,转移就先放一个'I',再放一个'O'看能够转移到哪些位置. 现代豪宅 把起点.终点和所有有开关的点建两个点分别表示南北和东西方向,\(x\)相同.\(y\)相邻的两个点南北方向连距离的边,\(y\)相同.\(x\)…

问题描述 给你一根长度为 n 的绳子,请把绳子剪成整数长度的 m 段(m.n都是整数,n>1并且m>1),每段绳子的长度记为 k[0],k[1]...k[m] .请问 k[0]*k[1]*...*k[m] 可能的最大乘积是多少?例如,当绳子的长度是8时,我们把它剪成长度分别为2.3.3的三段,此时得到的最大乘积是18. 示例 1: 输入: 2 输出: 1 解释: 2 = 1 + 1, 1 × 1 = 1 示例 2: 输入: 10 输出: 36 解释: 10 = 3 + 3 + 4, 3 × 3…

2022美团Java后端开发春招实习面经 一面 1.讲一下计算机网络的五层架构,每层分别有什么协议 ​ 五层架构:应用层.运输层.网络层.数据链路层.物理层 ​ 2.什么是 Http 协议,各种 Http 协议状态码的含义 ​ HTTP 是超⽂本传输协议,也就是HyperText Transfer Protocol ​ HTTP协议拆解为超文本.传输.协议.可以理解为HTTP是一个在计算机世界里专门在两点之间传输文字.图片.音频视频等超文本数据的约定和规范,至于为什么是在两点间,而不是最常见的C…

Leetcode之动态规划(DP)专题-198. 打家劫舍(House Robber) 你是一个专业的小偷,计划偷窃沿街的房屋.每间房内都藏有一定的现金,影响你偷窃的唯一制约因素就是相邻的房屋装有相互连通的防盗系统,如果两间相邻的房屋在同一晚上被小偷闯入,系统会自动报警. 给定一个代表每个房屋存放金额的非负整数数组,计算你在不触动警报装置的情况下,能够偷窃到的最高金额. 示例 1: 输入: [1,2,3,1] 输出: 4 解释: 偷窃 1 号房屋 (金额 = 1) ,然后偷窃 3 号房屋 (金额…

You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed, the only constraint stopping you from robbing each of them is that adjacent houses have security system connected and it will autom…

You are a professional robber planning to rob houses along a street. Each house has a certain amount of money stashed. All houses at this place are arranged in a circle. That means the first house is the neighbor of the last one. Meanwhile, adjacent…