HDU 3062 && HDU 1824 && POJ 3678 && BZOJ 1997 2-SAT

一条边<u,v>表示u选那么v一定被选。

#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
using namespace std;
const int Maxm=21000;
const int Maxn=2010;
struct EDGE{int to,next;}edge[Maxm];
int T,m,Stack[Maxn],head[Maxn],Belong[Maxn],Id[Maxn],Dfn[Maxn],Low[Maxn],h1,h2,h,Stamp,scc,top,cnt;
bool vis[Maxn];
inline int Min(int x,int y) {return x>y?y:x;}
inline void Add(int u,int v){edge[cnt].to=v;edge[cnt].next=head[u];head[u]=cnt++;}
inline bool Check()
{
    for (int i=0;i<T;i++) if (Belong[i<<1]==Belong[i<<1|1]) return false;
    return true;
}
void Tarjan(int u)
{
    Stack[++top]=u; vis[u]=true;
    Low[u]=Dfn[u]=++Stamp;
    for (int i=head[u];i!=-1;i=edge[i].next)
        if (Dfn[edge[i].to]==-1) Tarjan(edge[i].to),Low[u]=Min(Low[u],Low[edge[i].to]); else 
        if (vis[edge[i].to]) Low[u]=Min(Low[u],Dfn[edge[i].to]);
    if (Dfn[u]==Low[u])
    {
        while (true)
        {
            int v=Stack[top--];
            Belong[v]=scc;
            vis[v]=false;
            if (u==v) break;
        }
        scc++;
    }
}

int main()
{
    
    while (scanf("%d%d",&T,&m)!=EOF)
    {
        for (int i=0;i<T;i++)
        {
            scanf("%d%d%d",&h,&h1,&h2);
            Id[h]=i<<1;
            Id[h1]=Id[h2]=i<<1|1;
        }
        memset(head,-1,sizeof(head));
        memset(Dfn,-1,sizeof(Dfn));
        cnt=Stamp=top=0;
        for (int i=1;i<=m;i++)
        {    
            scanf("%d%d",&h1,&h2);
            Add(Id[h1],Id[h2]^1),Add(Id[h2],Id[h1]^1);
        }
    
        for (int i=0;i<T*2;i++) if (Dfn[i]==-1) Tarjan(i);
        puts(Check()?"yes":"no");
    }
    return 0;
}

 

#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
using namespace std;
const int Maxm=1000100;
const int Maxn=2010;
struct EDGE{int to,next;}edge[Maxm];
int head[Maxn],Dfn[Maxn],Low[Maxn],Belong[Maxn],scc,Stk[Maxn],top,cnt,Stamp,n,m;
int p1,p2,c1,c2;
bool vis[Maxn];
inline int Min(int x,int y) {return x>y?y:x;}
inline int Id(int num,int pos){return (num<<1)+pos+1;}
inline void Add(int u,int v) {edge[cnt].to=v;edge[cnt].next=head[u];head[u]=cnt++;}
inline bool Check()
{
    for (int i=0;i<n;i++) if (Belong[Id(i,0)]==Belong[Id(i,1)]) return false; 
    return true;
}
void Tarjan(int u)
{
    Stk[++top]=u; vis[u]=true;
    Dfn[u]=Low[u]=++Stamp;
    for (int i=head[u];i!=-1;i=edge[i].next)
        if (Dfn[edge[i].to]==-1) Tarjan(edge[i].to),Low[u]=Min(Low[u],Low[edge[i].to]); else 
        if (vis[edge[i].to]) Low[u]=Min(Low[u],Dfn[edge[i].to]);
    if (Low[u]==Dfn[u])
    {
        while (true)
        {
            int v=Stk[top--];
            vis[v]=false;
            Belong[v]=scc;
            if (v==u) break;
        }
        scc++;
    }
}
int main()
{
    while (scanf("%d%d",&n,&m)!=EOF)
    {
        memset(head,-1,sizeof(head));
        memset(Dfn,-1,sizeof(Dfn));
        memset(Belong,0,sizeof(Belong));
        cnt=top=scc=0;
        for (int i=1;i<=m;i++)
        {
            scanf("%d%d%d%d",&p1,&p2,&c1,&c2);
            Add(Id(p1,c1),Id(p2,1-c2)),Add(Id(p2,c2),Id(p1,1-c1));
        }
        for (int i=1;i<=2*n;i++) if (Dfn[i]==-1) Tarjan(i);
        puts(Check()?"YES":"NO");
    }
    return 0;
}

#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
using namespace std;
const int Maxn=2010;
const int Maxm=4010000;
int One[Maxn],Zero[Maxn],Stack[Maxn],Belong[Maxn],head[Maxn],Low[Maxn],Dfn[Maxn],n,m,u,v,w,cnt,Stamp,scc,top;
bool vis[Maxn];
char ch[20];
struct EDGE{int to,next;}edge[Maxm];
inline int Min(int x,int y){return x>y?y:x;}
inline void Add(int u,int v){edge[cnt].to=v;edge[cnt].next=head[u];head[u]=cnt++;}
inline bool Check() 
{
    for (int i=0;i<n;i++) if (Belong[One[i]]==Belong[Zero[i]]) return false;
    return true;
}
void Tarjan(int u)
{
    Stack[++top]=u; vis[u]=true;
    Low[u]=Dfn[u]=++Stamp;
    for (int i=head[u];i!=-1;i=edge[i].next)
        if (Dfn[edge[i].to]==-1) Tarjan(edge[i].to),Low[u]=Min(Low[u],Low[edge[i].to]); else 
        if (vis[edge[i].to]) Low[u]=Min(Low[u],Dfn[edge[i].to]);
    if (Low[u]==Dfn[u])
    {
        while (true)
        {
            int v=Stack[top--];
            vis[v]=false;
            Belong[v]=scc;
            if (u==v) break;
        }
        scc++;
    }
}
int main()
{
    scanf("%d%d",&n,&m);
    for (int i=0;i<n;i++) One[i]=i<<1,Zero[i]=i<<1|1;
    memset(head,-1,sizeof(head));
    memset(Dfn,-1,sizeof(Dfn));
    for (int i=1;i<=m;i++)
    {
        scanf("%d%d%d%s",&u,&v,&w,ch);
        if (ch[0]=='A')
        {
            if (w==1) Add(Zero[u],One[u]),Add(Zero[v],One[v]);
            if (w==0) Add(One[u],Zero[v]),Add(One[v],Zero[u]);
        }
        if (ch[0]=='O')
        {
            if (w==1) Add(Zero[u],One[v]),Add(Zero[v],One[u]);
            if (w==0) Add(One[v],Zero[v]),Add(One[u],Zero[u]);
        }
        if (ch[0]=='X')
        {
            if (w==1) Add(One[u],Zero[v]),Add(Zero[u],One[v]),Add(Zero[v],One[u]),Add(One[v],Zero[u]);
            if (w==0) Add(One[u],One[v]),Add(One[v],One[u]),Add(Zero[u],Zero[v]),Add(Zero[v],Zero[u]);
        }
    }
    
    for (int i=0;i<n<<1;i++) if (Dfn[i]==-1) Tarjan(i);
    puts(Check()?"YES":"NO");
    return 0;
}

#include <cstdio>
#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;
const int Maxm=80100;
int Stk[Maxm],Low[Maxm],Dfn[Maxm],head[Maxm],Belong[Maxm],In[Maxm],Out[Maxm],Pos[Maxm];
int cnt,top,Stamp,KASE,scc,n,m,x,u[Maxm],v[Maxm],tot;
bool vis[Maxm];
struct EDGE{int to,next;}edge[Maxm<<4];
inline int Min(int x,int y) {return x>y?y:x;}
inline void Swap(int &x,int &y) {int t=x;x=y;y=t;}
inline void Add(int u,int v) {edge[cnt].to=v;edge[cnt].next=head[u];head[u]=cnt++;}
inline bool Check()
{
    for (int i=1;i<=m;i++) if (Belong[In[i]]==Belong[Out[i]]) return false;
    return true;
}
void Tarjan(int u)
{
    Stk[++top]=u; vis[u]=true;
    Low[u]=Dfn[u]=++Stamp;
    for (int i=head[u];i!=-1;i=edge[i].next)
        if (Dfn[edge[i].to]==-1) Tarjan(edge[i].to),Low[u]=Min(Low[u],Low[edge[i].to]); else
        if (vis[edge[i].to]) Low[u]=Min(Low[u],Dfn[edge[i].to]);
    if (Low[u]==Dfn[u])
    {
        while (true)
        {
            int v=Stk[top--];
            vis[v]=false;
            Belong[v]=scc;
            if (u==v) break;
        }
        scc++;
    }
}
int main()
{
    scanf("%d",&KASE);
    for (int Kase=1;Kase<=KASE;Kase++)
    {
        scanf("%d%d",&n,&m);
        for (int i=1;i<=m;i++) scanf("%d%d",&u[i],&v[i]);
        for (int i=1;i<=n;i++) scanf("%d",&x),Pos[x]=i;
        if(m>3*n-6){puts("NO");continue;}
        for (int i=0;i<m;i++) In[i+1]=i<<1,Out[i+1]=i<<1|1;
        tot=0;
        for (int i=1;i<=m;i++) 
        {
            u[i]=Pos[u[i]],v[i]=Pos[v[i]];
            if (v[i]<u[i]) Swap(u[i],v[i]);
            if ((v[i]-u[i]==1) || (v[i]==n && u[i]==1)) continue;
            u[++tot]=u[i],v[tot]=v[i];
        }
        m=tot;
        memset(Dfn,-1,sizeof(Dfn));
        memset(head,-1,sizeof(head));
        memset(vis,false,sizeof(vis));
        Stamp=cnt=top=scc=0;
          
        for (int i=1;i<=m;i++)
            for (int j=i+1;j<=m;j++)
                if (((u[i]<u[j] && u[j]<v[i] && v[i]<v[j]) || (u[j]<u[i] && u[i]<v[j] && v[j]<v[i])))
                    Add(In[i],Out[j]),Add(In[j],Out[i]),Add(Out[i],In[j]),Add(Out[j],In[i]);
                  
        for (int i=0;i<m<<1;i++) if (Dfn[i]==-1) Tarjan(i);
        puts(Check()?"YES":"NO");
    }
    return 0;
}