混合图的欧拉回路判定方法: 1.首先判断基图是否连通,不连通的话表示不可能,否则进入下一步. 2.对于无向边,随便确定一个方向 3.确定好了之后,整张图就变成了有向图,计算每个节点的入度与出度 4.如果有一个节点的入度—出度是奇数,那么表示不可能,否则进入下一步 5.建立网络,新增一个原点s,和汇点t,然后建立网络 ; i<=M; i++) )//如果是有向边 AddEdge(u[i],v[i],); ; i<=N; i++) { if(Ru[i]>Chu[i]) AddEdge(i,t…

POJ 1637 Sightseeing tour 题目链接 题意:给一些有向边一些无向边,问能否把无向边定向之后确定一个欧拉回路 思路:这题的模型很的巧妙,转一个http://blog.csdn.net/pi9nc/article/details/12223693 先把有向边随意定向了,然后依据每一个点的入度出度之差,能够确定每一个点须要调整的次数,然后中间就是须要调整的边,容量为1,这样去建图最后推断从源点出发的边是否都满流就可以 代码: #include <cstdio> #includ…

Sightseeing tour Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 6986   Accepted: 2901 Description The city executive board in Lund wants to construct a sightseeing tour by bus in Lund, so that tourists can see every corner of the beauti…

嗯,这是我上一篇文章说的那本宝典的第二题,我只想说,真TM是本宝典……做的我又痛苦又激动……(我感觉ACM的日常尽在这张表情中了) 题目链接:http://poj.org/problem?id=1637 Time Limit: 1000MS Memory Limit: 10000K Description The city executive board in Lund wants to construct a sightseeing tour by bus in Lund, so that t…

Sightseeing tour Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 9276   Accepted: 3924 Description The city executive board in Lund wants to construct a sightseeing tour by bus in Lund, so that tourists can see every corner of the beauti…

Sightseeing tour   Description The city executive board in Lund wants to construct a sightseeing tour by bus in Lund, so that tourists can see every corner of the beautiful city. They want to construct the tour so that every street in the city is vis…

Sightseeing tour Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 8628   Accepted: 3636 Description The city executive board in Lund wants to construct a sightseeing tour by bus in Lund, so that tourists can see every corner of the beauti…

Sightseeing tour Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 6448   Accepted: 2654 Description The city executive board in Lund wants to construct a sightseeing tour by bus in Lund, so that tourists can see every corner of the beauti…

http://poj.org/problem?id=1637 题意:给出n个点和m条边,这些边有些是单向边,有些是双向边,判断是否能构成欧拉回路. 思路: 构成有向图欧拉回路的要求是入度=出度,无向图的要求是所有顶点的度数为偶数. 但不管是那个,顶点的度数若是奇数,那都是不能构成的. 这道题目是非常典型的混合图欧拉回路问题,对于双向边,我们先随便定个向,然后就这样先记录好每个顶点的入度和出度. 如果有顶点的度数为奇数,可以直接得出结论,是不能构成欧拉回路的. 那么,如果都是偶数呢? 因为还会存在…

题目:http://poj.org/problem?id=1637 先给无向边随便定向,如果一个点的入度大于出度,就从源点向它连 ( 入度 - 出度 / 2 ) 容量的边,意为需要流出去这么多:流出去1表示改了一条边的方向,会使自己出度-1.入度+1,所以容量要/2:出度大于入度的点类似地连向汇点:无向边按给它定的方向的反方向连上容量为1的边:最后看看能否满流即可. #include<cstdio> #include<cstring> #include<algorithm&g…