记$d_{G}(x,y)$表示无向图$G$中从$x$到$y$的最短路,设给定的图为$G=(V,E)$,$T$为其生成树,$E_{T}$为$T$的边集 下面,考虑计算$f(x,y)$-- 首先,对于一棵树$T$,$z$在$x$到$y$的路径上(包括$x$和$y$)当且仅当$d_{T}(x,z)+d_{T}(z,y)=d_{T}(x,y)$ 同时,由于$T$的性质,上述这三项都与$d_{G}$中相同,即等价于$d_{G}(x,z)+d_{G}(z,y)=d_{G}(x,y)$ 由于这与$T$无关,即…

Codeforces 1528D It's a bird! No, it's a plane! No, it's AaParsa!(*2500) 考虑以每个点为源点跑一遍最短路,每次取出当前距离最小的点然后更新一圈周围的点,具体更新方法是:设 \(p\) 为当前这一轮我们取出的点,那么显然对于一条本来由 \(p\to q\),权值为 \(c\) 的边以及另一个点 \(r\),有 \(d_r\leftarrow\min(d_r,c+d_p+(r-q+d_p)\bmod n)\),直接松弛单次复杂度…

You are asked to cut off trees in a forest for a golf event. The forest is represented as a non-negative 2D map, in this map: 0 represents the obstacle can't be reached. 1 represents the ground can be walked through. The place with number bigger than…

UVA.122 Trees on the level(二叉树 BFS) 题意分析 给出节点的关系,按照层序遍历一次输出节点的值,若树不完整,则输出not complete 代码总览 #include <iostream> #include <cstdio> #include <cstring> #include <algorithm> #include <queue> #include <vector> #define nmax 10…

Trees are fundamental in many branches of computer science (Pun definitely intended). Current state- of-the art parallel computers such are based on fat trees . Quad- and octal-trees are fundamental to many algorithms in computer graphics. This probl…

 Trees on the level UVA - 122  解题思路: 首先要解决读数据问题,根据题意,当输入为“()”时,结束该组数据读入,当没有字符串时,整个输入结束.因此可以专门编写一个readin()函数,类型设置为bool型,遇到第一种情况时返回true,遇到第二种情况返回false,主程序中只要发现readin返回false时就break,结束整个大循环. 接下来要建立二叉树,首先为二叉树编写一个结构体,然后根据字符串的输入情况来建树,如果是‘L’就往左走,走不动时建一颗新树,同样…

题意:给你一些字符串,代表某个值被插入树中的位置.让你输出层序遍历. 题解:动态建树. 由于输入复杂,将输入封装成read_input.注意输入函数返回的情况 再将申请新节点封装成newnode(). 最后层序输出直接用bfs实现. 坑:我把ans.clear放到主程序的if里面,导致某特定情况无法初始化,wa了一页//以后debug真的别XJB改细节了上下语句顺序,一些无关紧要的处理,改之前想一想 #define _CRT_SECURE_NO_WARNINGS #include "stdio.…

链接: https://codeforces.com/contest/1283/problem/D 题意:给定n个不同的整数点,让你找m个不同的整数点,使得这m个点到到这n个点最小距离之和最小. 思路:贪心一下,首先每个点的x+1和x-1两个坐标到这个点的距离是最短的,之后是x+2,x-2,再之后是x+3,x-3,那么可以想到bfs,首先把n个点存入队列中,找与他们距离为1的点,之后再bfs距离为2的点,如此这个过程直到找到m个点. AC代码: #include<iostream> #incl…

题意:将多叉树转化为括号表示法,每个非叶结点的正下方都有一个'|'然后下方是一排'-'和字符,恰好覆盖所有子结点的正上方,单独的一行'#'为数据的结束标志 解题思路:用gets将字符数组输入,本题不用建树,直接用广度优先递归求解,同时注意对空树的处理(需要单独判断),以及结点的符号不一定是字母,也可以是其他的符号(用isspace()判断是不是空格,并且单独判断是不是换行符'\0') 笔记:gets是从标准的输入接收一行字符,遇到'\n'时结束,但不接收'\n',把 '\n'留存输入缓冲区:把接…

1656: [Usaco2006 Jan] The Grove 树木 Time Limit: 5 Sec  Memory Limit: 64 MBSubmit: 186  Solved: 118[Submit][Status][Discuss] Description The pasture contains a small, contiguous grove of trees that has no 'holes' in the middle of the it. Bessie wonders…

For a undirected graph with tree characteristics, we can choose any node as the root. The result graph is then a rooted tree. Among all possible rooted trees, those with minimum height are called minimum height trees (MHTs). Given such a graph, write…

http://acm.hdu.edu.cn/showproblem.php?pid=1693 题意:n×m的棋盘求简单回路(可以多条)覆盖整个棋盘的方案,障碍格不许摆放.(n,m<=11) #include <cstdio> #include <cstring> #include <algorithm> using namespace std; typedef long long ll; struct H { static const int M=1000007;…

原题链接在这里:https://leetcode.com/problems/minimum-height-trees/ 题目: For a undirected graph with tree characteristics, we can choose any node as the root. The result graph is then a rooted tree. Among all possible rooted trees, those with minimum height a…

链接:http://www.bnuoj.com/bnuoj/problem_show.php?pid=25585 Current Server Time: 2013-08-27 20:42:26 Robots on a grid Time Limit: 3000ms Memory Limit: 65536KB   64-bit integer IO format: %lld      Java class name: Main Prev Submit Status Statistics Disc…

For a undirected graph with tree characteristics, we can choose any node as the root. The result graph is then a rooted tree. Among all possible rooted trees, those with minimum height are called minimum height trees (MHTs). Given such a graph, write…

For a undirected graph with tree characteristics, we can choose any node as the root. The result graph is then a rooted tree. Among all possible rooted trees, those with minimum height are called minimum height trees (MHTs). Given such a graph, write…

struct TreeNode{ int val; TreeNode* left; TreeNode* right; TreeNode(int val):val(val),left(NULL),right(NULL){} }; Not all binary trees are binary search trees. 4.1 Implement a function to check if a tree is balanced. For the purposes of this question…

Trees on the level Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 584    Accepted Submission(s): 195题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=1622 Problem Description Trees are fundamental…

You are asked to cut off trees in a forest for a golf event. The forest is represented as a non-negative 2D map, in this map: 0 represents the obstacle can't be reached. 1 represents the ground can be walked through. The place with number bigger than…

After a terrifying forest fire in Berland a forest rebirth program was carried out. Due to it N rows with M trees each were planted and the rows were so neat that one could map it on a system of coordinates so that the j-th tree in the i-th row would…

You are asked to cut off trees in a forest for a golf event. The forest is represented as a non-negative 2D map, in this map: 0 represents the obstacle can't be reached. 1 represents the ground can be walked through. The place with number bigger than…

题目链接:https://vjudge.net/contest/209862#problem/B 题目大意: Trees on the level Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 591    Accepted Submission(s): 200 Problem Description Trees are fundame…

https://www.geeksforgeeks.org/bfs-vs-dfs-binary-tree/ What are BFS and DFS for Binary Tree? A Tree is typically traversed in two ways: Breadth First Traversal (Or Level Order Traversal) Depth First Traversals Inorder Traversal (Left-Root-Right) Preor…

You are asked to cut off trees in a forest for a golf event. The forest is represented as a non-negative 2D map, in this map: 0 represents the obstacle can't be reached. 1 represents the ground can be walked through. The place with number bigger than…

Trees are fundamental in many branches of computer science. Current state-of-the art parallel computers such as Thinking Machines’ CM-5 are based on fat trees. Quad- and octal-trees are fundamental to many algorithms in computer graphics. This proble…

For a undirected graph with tree characteristics, we can choose any node as the root. The result graph is then a rooted tree. Among all possible rooted trees, those with minimum height are called minimum height trees (MHTs). Given such a graph, write…

For a undirected graph with tree characteristics, we can choose any node as the root. The result graph is then a rooted tree. Among all possible rooted trees, those with minimum height are called minimum height trees (MHTs). Given such a graph, write…

原题链接在这里:https://leetcode.com/problems/cut-off-trees-for-golf-event/description/ 题目: You are asked to cut off trees in a forest for a golf event. The forest is represented as a non-negative 2D map, in this map: 0 represents the obstacle can't be reach…

http://www.lydsy.com/JudgeOnline/problem.php?id=1656 神bfs! 我们知道,我们要绕这个联通的树林一圈. 那么,我们想,怎么才能让我们的bfs绕一个圈做bfs呢 我们可以这样:从联通的任意边界点引一条交边界的射线. 为什么呢?因为这样当我们的bfs到这条射线时,我们可以不向射线拓展! 可是我们考虑的是绕一个圈,那么我们要考虑从另一个放向到达射线的情况(即饶了一圈后到射线我们要考虑拓展) 这样我们就能保证绕了联通块一圈,然后是最短距离 具体细节看…

紫书:P150 uva122 Background Trees are fundamental in many branches of computer science. Current state-of-the art parallel computers such as Thinking Machines' CM-5 are based on fat trees. Quad- and octal-trees are fundamental to many algorithms in comp…