POJ 3905 Perfect Election id=3905" target="_blank" style="">题目链接 思路:非常裸的2-sat,就依据题意建边就可以 代码: #include <cstdio> #include <cstring> #include <cstdlib> #include <vector> #include <algorithm> using nam…

2-SAT 裸题,搞之 #include<cstdio> #include<cstring> #include<cmath> #include<stack> #include<vector> #include<algorithm> using namespace std; +; int N,M; ],s2[]; stack<int>S; vector<int>G[maxn]; vector<int>…

Perfect Election Time Limit: 5000MS   Memory Limit: 65536K Total Submissions: 438   Accepted: 223 Description In a country (my memory fails to say which), the candidates {1, 2 ..., N} are running in the parliamentary election. An opinion poll asks th…

题意:有N个人参加选举,有M个条件,每个条件给出:i和j竞选与否会只要满足二者中的一项即可.问有没有方案使M个条件都满足. 分析:读懂题目即可发现是2-SAT的问题.因为只要每个条件中满足2个中的一个即可,因此将人i拆成 点i表示不竞选,和点i+N表示竞选,根据合取式的满足条件建图跑Tarjan. 最后检查每个i与i+N是否在同一强连通分量中. #include<stdio.h> #include<iostream> #include<algorithm> #inclu…

加深了对有向边意义的理解了.2-SAT #include <iostream> #include <cstdio> #include <cstring> #include <algorithm> #include <cmath> using namespace std; ; ; int head[MAXN],dfn[MAXN],low[MAXN],st[MAXN],stop,belong[MAXN],tot,index,pat; bool sta…

2-sat总结 2-sat问题,一般表现的形式为.每一个点有两种方式a,b,要么选a,要么选b.而且点点之间有一些约束关系.比如:u和v至少一个选a.那么这就是一个表达式.把a当成真,b当成假,那就是u真或v真.2-sat的题目就是这样.给定这些约束,推断是否会矛盾 注意表达式的转化形式,(事实上就是离散数学中那几种转换方式) 比方(u真且v真)或(u假且v假)就能够转化成(u真或v假)且(u假或v真),这样就能建立关系 2-sat中的原理,事实上和2染色是一样的,把每一个结点拆分成一个真结点和…

转自——http://blog.csdn.net/qwe20060514/article/details/8112550 =============================以下是最小生成树+并查集======================================[HDU]1213   How Many Tables   基础并查集★1272   小希的迷宫   基础并查集★1325&&poj1308  Is It A Tree?   基础并查集★1856   More i…

Halloween treats Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 7644   Accepted: 2798   Special Judge Description Every year there is the same problem at Halloween: Each neighbour is only willing to give a certain total number of sweets…

Find a multiple Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 7192   Accepted: 3138   Special Judge Description The input contains N natural (i.e. positive integer) numbers ( N <= 10000 ). Each of that numbers is not greater than 15000…

The Pilots Brothers' refrigerator Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 22286   Accepted: 8603   Special Judge Description The game “The Pilots Brothers: following the stripy elephant” has a quest where a player needs to open a…