然后把 grid 上标记为 true 的小方格的面积加起来就可以了。 View Code 第二部分---树状数组:https://leetcode.com/tag/binary-indexed-tree/ 【218】The Skyline Problem(2019年1月22日) 本题想不出来用树状数组怎么做,最后自己yy出来了一种写法来做。 给了一堆大楼,给了每个楼的坐标和
public List<List<Integer>> pathSum(TreeNode root, int sum) { if (root == null) return res; List<Integer> list = new ArrayList<>(); this.backTrack(list, root, sum); return res; } void backTrack(List<Integer> list, TreeNode node, int sum) { if (node == null) return ; list....
leetcode.437同样是通过【前缀和之差】来求区间和的问题,同样使用哈希表来查找需要的前缀和。leetcode.437在这题的基础上结合了DFS,难度更高一些。 leetcode.238同样是前缀累积的思路,只不过累积方式是求积而不是求和。 leetcode.309 存在多种状态的动态规划 题目链接:https://leetcode.com/problems... 这题是...
Time Complexity for tree construction is O(n). There are total 2n-1 nodes, and value of every node is calculated only once in tree construction. Time complexity to query is O(Logn). To query a sum, we process at most four nodes at every level and number of levels is O(Logn). The...
Leetcode: Range Sum Query - Mutable && Summary: Segment Tree,Givenanintegerarraynums,findthesumoftheelementsbetweenindicesiandj(i≤j),inclusive.Theupdate(i,val)functionmodifiesnumsbyupda...
Trie, Segment Tree,树状数组---Other Kinds of Tree 字典树(前缀树): Leetcode208 Implement Trie: class Trie { TrieNode root; //attribute, which can show a trie's identity /** Initialize your data structure here. */ public Trie() { //constuctor, which used to create a new trie instan...
SegTreeNode* root; vector<vector<int>>arr; } vector<pair<int,int>>height; // {idx, h} public:vector<vector<int>> getSkyline(vector<vector<int>>& buildings) { set<int>Set; for (auto& building: buildings) for (auto & building: buildings)...
在做两道区间检索题中接触到了线段树的概念,本文将其进行整理,文末几篇参考对线段树做了系统的介绍,结合两道leetcode题,对线段树的创建、查找、更新有了更深地掌握。文中不足,还望多多指正。 区域和检索 - 数组不可变 给定一个整数数组 nums,求出数组从索引 i 到 j (i ≤ j) 范围内元素的总和,包含 i,...
75 BLIND CURATED LEETCODE QUESTIONS: Array Two Sum #1 👯 ❓: Given an array of integers nums & an integer target, return indices of the two numbers such that they add up to target. 🐣: Given nums = [2, 7, 11, 15], target = 9, Because nums[0] + nums[1] = 2 + 7 = ...
线段树 Segment tree 是一种二叉树形数据结构,1977年由 Jon Louis Bentley 发明,用以存储区间或线段,并且允许快速查询结构内包含某一点的所有区间。 一个包含nn个区间的线段树,空间复杂度为O(n)O(n),查询的时间复杂度则为O(logn+k)O(logn+k),其中kk是符合条件的区间数量。线段树的数据结构也可推广到高维度。