POJ 1236 :http://poj.org/problem?id=1236 参考:https://www.cnblogs.com/TnT2333333/p/6875680.html 题意: 有好多学校,每个学校可以给其他特定的学校发送文件.第一个问题是最少要给几个学校发文件,可以使得全部的学校收到文件.第二个问题是最少要加几条线路,使得随意挑一个学校发文件,也能使得全部的学校收到文件. 思路: 第一个问题,可以用tarjan给图中先缩点,因为强连通的环相互可达.所以只要数出缩完点后图中入度…

POJ 1236 Network of Schools(强连通 Tarjan+缩点) ACM 题目地址:POJ 1236 题意:  给定一张有向图,问最少选择几个点能遍历全图,以及最少加入�几条边使得有向图成为一个强连通图. 分析:  跟HDU 2767 Proving Equivalences(题解)一样的题目,只是多了个问题,事实上转化成DAG后就不难考虑了,事实上仅仅要选择入度为0的点即可了. 代码: /* * Author: illuz <iilluzen[at]gmail.com>…

题目链接: Poj 1236 Network of Schools 题目描述: 有n个学校,学校之间有一些单向的用来发射无线电的线路,当一个学校得到网络可以通过线路向其他学校传输网络,1:至少分配几个网络才能够让所有学校被网络覆盖?2:至少要加几条线路就能做到在任意一个学校安装网络都可以覆盖全部学校? 解题思路: 先用Tarjan对强连通分量进行缩点,然后对缩点以后的图进行处理,统计图中节点出度为零的有多少,入度为零的有多少个? 因为入度为零的点不能由其他的点到达,在每个入度为零的节点安装网络可…

POJ 1236 Network of Schools 题目链接 题意:题意本质上就是,给定一个有向图,问两个问题 1.从哪几个顶点出发,能走全全部点 2.最少连几条边,使得图强连通 思路: #include <cstdio> #include <cstring> #include <vector> #include <stack> using namespace std; const int N = 105; int n; vector<int>…

http://poj.org/problem?id=1236 Network of Schools Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 9481   Accepted: 3767 Description A number of schools are connected to a computer network. Agreements have been developed among those schoo…

http://poj.org/problem?id=1236 Network of Schools Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 13046   Accepted: 5215 Description A number of schools are connected to a computer network. Agreements have been developed among those scho…

主题链接: http://poj.org/problem?id=1236 Network of Schools Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 11433   Accepted: 4551 Description A number of schools are connected to a computer network. Agreements have been developed among thos…

Network of Schools Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 16806   Accepted: 6643 Description A number of schools are connected to a computer network. Agreements have been developed among those schools: each school maintains a li…

Network of Schools Description A number of schools are connected to a computer network. Agreements have been developed among those schools: each school maintains a list of schools to which it distributes software (the “receiving schools”). Note that…

Network of Schools A number of schools are connected to a computer network. Agreements have been developed among those schools: each school maintains a list of schools to which it distributes software (the “receiving schools”). Note that if B is in t…

Network of Schools Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 22729   Accepted: 8926 Description A number of schools are connected to a computer network. Agreements have been developed among those schools: each school maintains a li…

Network of Schools Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 12240   Accepted: 4871 Description A number of schools are connected to a computer network. Agreements have been developed among those schools: each school maintains a li…

Network of Schools Time Limit:1000MS     Memory Limit:10000KB     64bit IO Format:%I64d & %I64u Submit Status Practice POJ 1236 Description A number of schools are connected to a computer network. Agreements have been developed among those schools: e…

Network of Schools Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 16803   Accepted: 6641 Description A number of schools are connected to a computer network. Agreements have been developed among those schools: each school maintains a li…

Network of Schools Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 9073   Accepted: 3594 Description A number of schools are connected to a computer network. Agreements have been developed among those schools: each school maintains a lis…

Network of Schools Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 22745   Accepted: 8929 Description A number of schools are connected to a computer network. Agreements have been developed among those schools: each school maintains a li…

Network of Schools Description A number of schools are connected to a computer network. Agreements have been developed among those schools: each school maintains a list of schools to which it distributes software (the “receiving schools”). Note that…

Network of Schools Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 13800   Accepted: 5504 Description A number of schools are connected to a computer network. Agreements have been developed among those schools: each school maintains a li…

题目链接:http://poj.org/problem?id=1236 题意:给定一个表示n所学校网络连通关系的有向图.现要通过网络分发软件,规则是:若顶点u,v存在通路,发给u,则v可以通过网络从u接收到. 现要求解两个问题: TaskA: 最少分发给几个学校,就可以使所有的学校都能得到软件. TaskB: 最少增加几条边,就可以使得,发软件给任一学校,所有学校都可以收到. 思路:先进行强联通分量分解,然后缩点,并计算缩点后每个点的出度.入度.入度为0的点的总数为 a ,出度为0的点总数为 b…

poj.org/problem?id=1236 [题意] 给定一个有向图,求: (1)至少要选几个顶点,才能做到从这些顶点出发,可以到达全部顶点 (2)至少要加多少条边,才能使得从任何一个顶点出发,都能到达全部顶点 [思路] (1)强连通分量缩点后形成一个有向无环图,只要选择入度为0的顶点,其他顶点都可以被到达 (2)等价于一个有向无环图加最少加多少条边能够变成一个强连通图,取出度为0的点的个数和入度为0的点的个数的max,因为出度为0的点要加一条出边,入度为0的点要加一条入边 (2)特判特殊情…

传送门 Description A number of schools are connected to a computer network. Agreements have been developed among those schools: each school maintains a list of schools to which it distributes software (the “receiving schools”). Note that if B is in the…

题意:给出一个有向图.1:问至少选出多少个点,才能沿有向边遍历所有节点.2:问至少加多少条有向边,使原图强连通. 分析:第一个问题,缩点后找所有树根(入度为0).第二个问题,分别找出入度为0和出度为0的所有点,去最大值即为答案. 关于第二个问题,与这道题很相似. #include<cstdio> #include<cstring> #include<stack> #include<algorithm> using namespace std; ; struc…

思路:使用tarjan求强连通分量并进行缩点,判断所有入度为0的点,这个点就是必须要给予文件的点,分别计算出度,入度为零的点的个数,取二者的最大值就是把这个图变成强连通需要加的边数. 一个取值需要讨论,当这个图就是强连通图的时候,答案输出1和0. 个人经历:作为初学者这个题错了很多遍,学姐给我们讲的在某个点已经被访问过的时候low值是否更新的问题,使用的是id的判断方法,只有当id为零的时候才能更新low值,这个现在我是理解的,但当时因为错误太多看别人的代码时,看到了是否在栈中的记录方式,当时我…

题目大意:有向图连通图,第一问求至少需要多少个软件才能传输到所有学校,第二问求至少需要增加多少条路使其成为强连通图 题目思路:利用Tarjan算法经行缩点,第一问就是求缩点后入度为0的点的个数(特殊情况,当缩点后仅剩一个点是输出0),第二问就是求缩点后max(入度为0的点的个数,出度为0的点的个数). #include<stdio.h> #include<string.h> #include<stdlib.h> #include<math.h> #inclu…

<题目链接> 题目大意: 有N个学校,每个学校之间单向可以发送软件,现在给你一些学校之间的收发关系.问你下面两个问题:至少要给多少个学校发送软件才能使得最终所有学校都收到软件:至少要多加多少个关系才能使得向任意一个学校发送一套软件,每个学校都能收到软件.  解题分析: 首先,对该图进行缩点,显然第一问问的就是,缩点后的入度为0的联通块的数量(因为这些点没有入度,必须人为的给它们软件,它们才能接收到软件):第二问,显然就是问至少要加多少条边,使得该图变为强连通图,强连通图有个条件,就是所有的点一…

题意: 求一个有向图中: (1)要选几个点才能把的点走遍 (2)要添加多少条边使得整个图强联通 分析: 对于问题1, 我们只要求出缩点后的图有多少个入度为0的scc就好, 因为有入度的scc可以从其他地方到达. 对于问题2, 每个入度为0的scc, 都可以补一条边可以变成强连通图, 每个出度为0的scc, 也可以补一条边使其变成强连通图. 所以答案就是max(入度为0scc个数,出度为0scc个数). #include<cstdio> #include<iostream> #inc…

题目大意:有N个学校和一些有向边将它们连结,求: 1.最少需要向几个学校发放软件,使得他们中的每一个学校最终都能够获得软件. 2.最少需要增加几条有向边使得可以从任意一个学校发放软件,使得每一个学校最终都能够获得软件. 分析: 1.缩点以后,找出入度为0的点的个数即可(因为没人可以给他们软件). 2.缩点以后,答案即是max(入度为0的点,出度为0的点).因为只要另每一对入度为0和出度为0的点相连接即可. 第二个问题也有无向图的版本,那样的话处理方法是:缩点以后,找出那些度为1的点,个数为cnt…

题目大概: 每个学校都可以把软件复制好,交给它名单上的学校. 问题A:把软件复制成几份,然后交给不同的学校,所有学校才能够都有软件. 问题B:添加几条边,能使得这个图变成强连通图. 思路: 找出所有的强连通分量,然后缩点,变成一个新有向无环图,求每个强连通分量的入度和出度. A:入度是0的点就是复制的最小数量,因为只要给强连通分量一个软件,他就会传到每个点,所以找出没有入口的强连通分量的数量就是要复制的数量(其他强连通分量都可以由这些分量传递过去). B:in0为入度为0点的数量,out0出度为…

题目链接:http://poj.org/problem?id=1236 题目大意:有一些学校,学校之间可以进行收发邮件,给出学校的相互关系,问:1.至少 要向这些学校发送多少份才能使所有的学校都能获得邮件:2.若想只发送一份即可让所有学 校都能收到邮件,则至少需要需要再进行多少次学校之间的连接. 学校之间的关系可构成图,将图进行强连通缩点成块儿后可知,每个进入数为0的点需要发 送一份:若想要所有点都连接,则需要连接数目为max(入度为0点数,出度为0点数),这 个是结论,详细证明不再贴. 代码如…

题目链接:http://poj.org/problem?id=1236题目大意:给出N台电脑,电脑间单向连通传送文件问题1.网络中最少放几个文件保证所有电脑都能接受到文件问题2.最少向网络中加几条线保证任意放1个文件所有电脑都能接受到解题思路:1.求出强连通分量2.缩点 ,进行重新构图3.如果入度为0,说明没有文件传输到该网络.解决问题1,统计入度为0的个数即可4.一个强连通图的入度和出度都不为0.入度为0相当于根root,出度为0相当于叶子leave.max(root, leave)即为答案.…