Intro: 在OI中,前缀和是一种泛用性很高的数据结构,也是非常重要的优化思想 Function: 求静态区间和 模板题:输入序列\(a_{1..n}\),对于每一个输入的二元组\((l,r)\),求\(\sum_{i=l}^ra_i\) 先想一想朴素算法怎么做吧 对于输入的每一组\((l,r)\),遍历序列\(a_{l..r}\)求和,代码如下 int s(0); for(int i(l);i<=r;++i)s+=a[i]; return s; Time complexity: \(O(n)…

Design and implement a TwoSum class. It should support the following operations: add and find. add - Add the number to an internal data structure.find - Find if there exists any pair of numbers which sum is equal to the value. For example, add(1); ad…

Intro: 作为查询界的\(O(1)\)王者--前缀和的亲兄弟,差分,他可是修改界的\(O(1)\)王者 Prerequisite knowledge: 前缀和 Function: 仅单次询问的区间修改 模板题:洛谷P2367 语文成绩 先想一想朴素算法怎么做吧 对于输入的每一组\((x,y)\),遍历序列\(a_{x..y}\),每一项加上\(z\),代码如下 while(p--)for(int i(x);i<=y;++i)a[i]+=z; Time complexity: \(O(np)\…

字典树(查找树) 26个分支作用:检测字符串是否在这个字典里面插入.查找 字典树与哈希表的对比:时间复杂度:以字符来看:O(N).O(N) 以字符串来看:O(1).O(1)空间复杂度:字典树远远小于哈希表 前缀相关的题目字典树优于哈希表字典树可以查询abc是否有ab的前缀 字典树常考点:1.字典树实现2.利用字典树前缀特性解题3.矩阵类字符串一个一个字符深度遍历的问题(DFS+trie) dfs树和trie树同时遍历 word searchIIdfs+hash:时间复杂度大,后面遍历到有些字符就…

字典树(Trie树相关) 208. Implement Trie (Prefix Tree) Implement a trie with insert, search, and startsWith methods. (Medium) Note:You may assume that all inputs are consist of lowercase letters a-z. 分析: 字典树即前缀匹配树,在空间不是很影响的情况下一般采用如下数据结构存储Trie节点 class TrieNod…

Design and implement a TwoSum class. It should support the following operations:add and find. add - Add the number to an internal data structure.find - Find if there exists any pair of numbers which sum is equal to the value. For example,add(1); add(…

原题链接在这里:https://leetcode.com/problems/two-sum-iii-data-structure-design/ 题目: Design and implement a TwoSum class. It should support the following operations: add and find. add - Add the number to an internal data structure.find - Find if there exists…

题目链接: Basic Data Structure Time Limit: 7000/3500 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 207    Accepted Submission(s): 41 Problem Description Mr. Frog learned a basic data structure recently, which is called…

Design and implement a TwoSum class. It should support the following operations: add and find. add - Add the number to an internal data structure.find - Find if there exists any pair of numbers which sum is equal to the value. 这个解法很容易想到,但很容易超时. 基本来说有…

Basic Data Structure Time Limit: 7000/3500 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others) Problem Description Mr. Frog learned a basic data structure recently, which is called stack.There are some basic operations of stack: ∙ PUSH x: p…