Divide Tree(0785) 问题描述 As we all know that we can consider a tree as a graph. Now give you a tree with nodes having its weight. We define the weight of a tree is the sum of the weight of all nodes on it. You know we can divide the tree into two subtr…

Huge Tree(0856) 问题描述 There are N trees in a forest. At first, each tree contains only one node as its root. And each node is marked with a number. You're asked to do the following two operations: A X Y, you need to link X's root to Y as a direct chil…

题目描述:Divide Tree   As we all know that we can consider a tree as a graph. Now give you a tree with nodes having its weight. We define the weight of a tree is the sum of the weight of all nodes on it. You know we can divide the tree into two subtrees…

前言 第一天的算法都还没有缓过来,直接就进入了第二天的算法学习.前一天一直在整理Binary Search的笔记,也没有提前预习一下,好在Binary Tree算是自己最熟的地方了吧(LeetCode上面Binary Tree的题刷了4遍,目前95%以上能够Bug Free)所以还能跟得上,今天听了一下,觉得学习到最多的,就是把Traverse和Divide Conquer分开来讨论,觉得开启了一片新的天地!今天写这个博客我就尽量把两种方式都写一写吧. Outline: 二叉树的遍历 前序遍历t…

参考[LeetCode] questions conlusion_InOrder, PreOrder, PostOrder traversal 可以对binary tree进行遍历. 此处说明Divide and Conquer 的做法,其实跟recursive的做法很像,但是将结果存进array并且输出,最后conquer (这一步worst T:O(n)) 起来,所以时间复杂度可以从遍历O(n) -> O(n^2). 实际上代码是一样, 就是把[root.val] 放在先, 中, 后就是pr…

Given a non-empty binary tree, find the maximum path sum. For this problem, a path is defined as any sequence of nodes from some starting node to any node in the tree along the parent-child connections. The path must contain at least one node and doe…

一. 1. Lowest Common Ancestor class Solution { public: TreeNode *lowestCommonAncestor(TreeNode *root, TreeNode *A, TreeNode *B) { if (root == NULL || root == A || root == B) { return root; } TreeNode* left = lowestCommonAncestor(root->left, A, B); Tre…

Link: P3806 传送门 Solution: 询问树上是否存在两点间的距离为$k$,共有$m$次询问($m\le 100,k\le 1e7$) 预处理出所有距离的可能性再$O(1)$出解的复杂度为$O(n^2*log(n))$,明显TLE(但好像并不会) 而如果直接在线处理要分治$m$次,找$m$次完全相同的重心,完全没有必要 因此最好采用离线处理的方式 在每个点运用$set$对于每一个$k$查询$k-dist(i)$在之前的子树中是否出现过 预估复杂度和在线其实没什么区别,都为$O(n*…

C. Digit Tree time limit per test:3 seconds memory limit per test:256 megabytes input:standard input output:standard output ZS the Coder has a large tree. It can be represented as an undirected connected graph of n vertices numbered from 0 to n - 1 a…

Given a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree. According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between two nodes v and w as the lowest node in T that has both v and w…

Query on a tree Time Limit: 5000ms Memory Limit: 262144KB   This problem will be judged on SPOJ. Original ID: QTREE64-bit integer IO format: %lld      Java class name: Main Prev Submit Status Statistics Discuss Next Font Size: + - Type:   None Graph…

Given a binary tree, find the maximum path sum. The path may start and end at any node in the tree. Example Given the below binary tree: 1 / \ 2 3 return 6. For this problem we need to think about the problem in this way. Now we want the largest sum…

1 /** * Definition of TreeNode: * public class TreeNode { * public int val; * public TreeNode left, right; * public TreeNode(int val) { * this.val = val; * this.left = this.right = null; * } * } */ public class Solution { /** * @param root: The root…

A Complete Tutorial on Tree Based Modeling from Scratch (in R & Python) MACHINE LEARNING PYTHON R   SHARE      MANISH SARASWAT, APRIL 12, 2016 / 52     Introduction Tree based learning algorithms are considered to be one of the best and mostly used s…

Given a sorted (increasing order) array, write an algorithm to create a binary tree with minimal height. 1.Divide the array equally into left part and right part, the mid value will be the root. 2.Recall the function to the left and right part of the…

divide and conquer on tree. #include <map> #include <vector> #include <cstdio> #include <cstdlib> #include <cstring> #include <iostream> using namespace std; const int N = 5e4+10; const int K = 32; typedef long long LL;…

Problem: Given n nodes labeled from 0 to n - 1 and a list of undirected edges (each edge is a pair of nodes), write a function to check whether these edges make up a valid tree. For example: Given n = 5 and edges = [[0, 1], [0, 2], [0, 3], [1, 4]], r…

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Convert a BST to a sorted circular doubly-linked list in-place. Think of the left and right pointers as synonymous to the previous and next pointers in a doubly-linked list. Let's take the following BST as an example, it may help you understand the p…

[AtCoder3611]Tree MST(点分治,最小生成树) 题面 AtCoder 洛谷 给定一棵\(n\)个节点的树,现有有一张完全图,两点\(x,y\)之间的边长为\(w[x]+w[y]+dis(x,y)\),其中\(dis\)表示树上两点的距离. 求完全图的\(MST\). 题解 首先连边的这个式子可以直接转换成树上的两点间的路径,所以接下来只考虑\(dis(x,y)\). 考虑\(Boruvka\)算法的执行过程,每次都会选择到达一个点集最近的一个点,然后将他们连边. 现在考虑模拟这…

Given a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree. According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between two nodes p and q as the lowest node in T that has both p and q…

［抄题］: Given a binary tree, write a function to get the maximum width of the given tree. The width of a tree is the maximum width among all levels. The binary tree has the same structure as a full binary tree, but some nodes are null. The width of one…

C++ Traverse /** * Definition of TreeNode: * class TreeNode { * public: * int val; * TreeNode *left, *right; * TreeNode(int val) { * this->val = val; * this->left = this->right = NULL; * } * } */ class Solution { public: /** * @param root: a Tree…

Given an n-ary tree, return the preorder traversal of its nodes' values. For example, given a 3-ary tree: Return its preorder traversal as: [1,3,5,6,2,4]. 这个题目思路就是跟LeetCode questions conlusion_InOrder, PreOrder, PostOrder traversal类似, recursive 和iter…

Path in Tree: [LeetCode] 112. Path Sum_Easy tag: DFS       input: root, target,   return True if exists sum(root-> leaf) == target else False       1 [LeetCode] 257. Binary Tree Paths_ Easy tag: DFS        input: root,   return all paths from root to…

Given a non-empty binary tree, find the maximum path sum. For this problem, a path is defined as any sequence of nodes from some starting node to any node in the tree along the parent-child connections. The path must contain at least one node and doe…

In the previous post, we talk about a very popular Boosting algorithm - Gradient Boosting Decision Tree. The key of GBM is using Gradient Descent to optimize the loss function. But why Gradient Descent, not other numeric optimization method? Is it th…

Given preorder and inorder traversal of a tree, construct the binary tree. Note: You may assume that duplicates do not exist in the tree. For example, given preorder = [3,9,20,15,7] inorder = [9,3,15,20,7] Return the following binary tree: 3 / \ 9 20…

RXD, tree and sequence Time Limit: 6000/3000 MS (Java/Others)    Memory Limit: 524288/524288 K (Java/Others)Total Submission(s): 234    Accepted Submission(s): 82 Problem Description RXD has a rooted tree T with size n, the root ID is 1, with the dep…

Given a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree. According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between two nodes v and w as the lowest node in T that has both v and w…