专题训练之2-sat

推荐几篇博客：https://blog.csdn.net/JarjingX/article/details/8521690 研究总结2-sat问题

https://blog.csdn.net/whereisherofrom/article/details/79417926 有向图强连通+2-sat问题

推荐几篇论文：https://wenku.baidu.com/view/afd6c436a32d7375a41780f2.html  由对称性问题解2-sat

https://wenku.baidu.com/view/0f96c3daa58da0116c1749bc.html 2-sat问题解法浅析

 

tarjan模板

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<algorithm>
 4 using namespace std;
 5 const int maxn=20010;
 6 const int maxm=50010;
 7 struct edge{
 8     int to,nxt;
 9 }edge[maxm];
10 int head[maxn],tot;
11 int low[maxn],dfn[maxn],stack[maxn],belong[maxn];
12 int index,top;
13 int scc;
14 bool vis[maxn];
15 int num[maxn];
16 
17 void addedge(int u,int v)
18 {
19     edge[tot].to=v;
20     edge[tot].nxt=head[u];
21     head[u]=tot++;
22 }
23 
24 void tarjan(int u)
25 {
26     int v;
27     low[u]=dfn[u]=++index;
28     stack[top++]=u;
29     vis[u]=true;
30     for ( int i=head[u];i!=-1;i=edge[i].nxt ) {
31         v=edge[i].to;
32         if ( !dfn[v] ) {
33             tarjan(v);
34             low[u]=min(low[u],low[v]);
35         }
36         else if ( vis[v] ) low[u]=min(low[u],dfn[v]);
37     }
38     if ( low[u]==dfn[u] ) {
39         scc++;
40         do {
41             v=stack[--top];
42             vis[v]=false;
43             belong[v]=scc;
44             num[scc]++;
45         }
46         while ( v!=u );
47     }
48 }
49 
50 void solve(int N)
51 {
52     memset(dfn,0,sizeof(dfn));
53     memset(vis,false,sizeof(vis));
54     memset(num,0,sizeof(num));
55     index=scc=top=0;
56     for ( int i=1;i<=N;i++ ) {
57         if ( !dfn[i] ) tarjan(i);
58     }
59 }
60 
61 void init()
62 {
63     tot=0;
64     memset(head,-1,sizeof(head));
65 }

tarjan