一条边<u,v>表示u选那么v一定被选。
1 #include <iostream>
2 #include <cstring>
3 #include <cstdio>
4 #include <algorithm>
5 using namespace std;
6 const int Maxm=21000;
7 const int Maxn=2010;
8 struct EDGE{int to,next;}edge[Maxm];
9 int T,m,Stack[Maxn],head[Maxn],Belong[Maxn],Id[Maxn],Dfn[Maxn],Low[Maxn],h1,h2,h,Stamp,scc,top,cnt;
10 bool vis[Maxn];
11 inline int Min(int x,int y) {return x>y?y:x;}
12 inline void Add(int u,int v){edge[cnt].to=v;edge[cnt].next=head[u];head[u]=cnt++;}
13 inline bool Check()
14 {
15 for (int i=0;i<T;i++) if (Belong[i<<1]==Belong[i<<1|1]) return false;
16 return true;
17 }
18 void Tarjan(int u)
19 {
20 Stack[++top]=u; vis[u]=true;
21 Low[u]=Dfn[u]=++Stamp;
22 for (int i=head[u];i!=-1;i=edge[i].next)
23 if (Dfn[edge[i].to]==-1) Tarjan(edge[i].to),Low[u]=Min(Low[u],Low[edge[i].to]); else
24 if (vis[edge[i].to]) Low[u]=Min(Low[u],Dfn[edge[i].to]);
25 if (Dfn[u]==Low[u])
26 {
27 while (true)
28 {
29 int v=Stack[top--];
30 Belong[v]=scc;
31 vis[v]=false;
32 if (u==v) break;
33 }
34 scc++;
35 }
36 }
37
38 int main()
39 {
40
41 while (scanf("%d%d",&T,&m)!=EOF)
42 {
43 for (int i=0;i<T;i++)
44 {
45 scanf("%d%d%d",&h,&h1,&h2);
46 Id[h]=i<<1;
47 Id[h1]=Id[h2]=i<<1|1;
48 }
49 memset(head,-1,sizeof(head));
50 memset(Dfn,-1,sizeof(Dfn));
51 cnt=Stamp=top=0;
52 for (int i=1;i<=m;i++)
53 {
54 scanf("%d%d",&h1,&h2);
55 Add(Id[h1],Id[h2]^1),Add(Id[h2],Id[h1]^1);
56 }
57
58 for (int i=0;i<T*2;i++) if (Dfn[i]==-1) Tarjan(i);
59 puts(Check()?"yes":"no");
60 }
61 return 0;
62 }
HDU 1824
1 #include <iostream>
2 #include <cstring>
3 #include <cstdio>
4 #include <algorithm>
5 using namespace std;
6 const int Maxm=1000100;
7 const int Maxn=2010;
8 struct EDGE{int to,next;}edge[Maxm];
9 int head[Maxn],Dfn[Maxn],Low[Maxn],Belong[Maxn],scc,Stk[Maxn],top,cnt,Stamp,n,m;
10 int p1,p2,c1,c2;
11 bool vis[Maxn];
12 inline int Min(int x,int y) {return x>y?y:x;}
13 inline int Id(int num,int pos){return (num<<1)+pos+1;}
14 inline void Add(int u,int v) {edge[cnt].to=v;edge[cnt].next=head[u];head[u]=cnt++;}
15 inline bool Check()
16 {
17 for (int i=0;i<n;i++) if (Belong[Id(i,0)]==Belong[Id(i,1)]) return false;
18 return true;
19 }
20 void Tarjan(int u)
21 {
22 Stk[++top]=u; vis[u]=true;
23 Dfn[u]=Low[u]=++Stamp;
24 for (int i=head[u];i!=-1;i=edge[i].next)
25 if (Dfn[edge[i].to]==-1) Tarjan(edge[i].to),Low[u]=Min(Low[u],Low[edge[i].to]); else
26 if (vis[edge[i].to]) Low[u]=Min(Low[u],Dfn[edge[i].to]);
27 if (Low[u]==Dfn[u])
28 {
29 while (true)
30 {
31 int v=Stk[top--];
32 vis[v]=false;
33 Belong[v]=scc;
34 if (v==u) break;
35 }
36 scc++;
37 }
38 }
39 int main()
40 {
41 while (scanf("%d%d",&n,&m)!=EOF)
42 {
43 memset(head,-1,sizeof(head));
44 memset(Dfn,-1,sizeof(Dfn));
45 memset(Belong,0,sizeof(Belong));
46 cnt=top=scc=0;
47 for (int i=1;i<=m;i++)
48 {
49 scanf("%d%d%d%d",&p1,&p2,&c1,&c2);
50 Add(Id(p1,c1),Id(p2,1-c2)),Add(Id(p2,c2),Id(p1,1-c1));
51 }
52 for (int i=1;i<=2*n;i++) if (Dfn[i]==-1) Tarjan(i);
53 puts(Check()?"YES":"NO");
54 }
55 return 0;
56 }
HDU 3062
1 #include <iostream>
2 #include <cstring>
3 #include <cstdio>
4 #include <algorithm>
5 using namespace std;
6 const int Maxn=2010;
7 const int Maxm=4010000;
8 int One[Maxn],Zero[Maxn],Stack[Maxn],Belong[Maxn],head[Maxn],Low[Maxn],Dfn[Maxn],n,m,u,v,w,cnt,Stamp,scc,top;
9 bool vis[Maxn];
10 char ch[20];
11 struct EDGE{int to,next;}edge[Maxm];
12 inline int Min(int x,int y){return x>y?y:x;}
13 inline void Add(int u,int v){edge[cnt].to=v;edge[cnt].next=head[u];head[u]=cnt++;}
14 inline bool Check()
15 {
16 for (int i=0;i<n;i++) if (Belong[One[i]]==Belong[Zero[i]]) return false;
17 return true;
18 }
19 void Tarjan(int u)
20 {
21 Stack[++top]=u; vis[u]=true;
22 Low[u]=Dfn[u]=++Stamp;
23 for (int i=head[u];i!=-1;i=edge[i].next)
24 if (Dfn[edge[i].to]==-1) Tarjan(edge[i].to),Low[u]=Min(Low[u],Low[edge[i].to]); else
25 if (vis[edge[i].to]) Low[u]=Min(Low[u],Dfn[edge[i].to]);
26 if (Low[u]==Dfn[u])
27 {
28 while (true)
29 {
30 int v=Stack[top--];
31 vis[v]=false;
32 Belong[v]=scc;
33 if (u==v) break;
34 }
35 scc++;
36 }
37 }
38 int main()
39 {
40 scanf("%d%d",&n,&m);
41 for (int i=0;i<n;i++) One[i]=i<<1,Zero[i]=i<<1|1;
42 memset(head,-1,sizeof(head));
43 memset(Dfn,-1,sizeof(Dfn));
44 for (int i=1;i<=m;i++)
45 {
46 scanf("%d%d%d%s",&u,&v,&w,ch);
47 if (ch[0]==‘A‘)
48 {
49 if (w==1) Add(Zero[u],One[u]),Add(Zero[v],One[v]);
50 if (w==0) Add(One[u],Zero[v]),Add(One[v],Zero[u]);
51 }
52 if (ch[0]==‘O‘)
53 {
54 if (w==1) Add(Zero[u],One[v]),Add(Zero[v],One[u]);
55 if (w==0) Add(One[v],Zero[v]),Add(One[u],Zero[u]);
56 }
57 if (ch[0]==‘X‘)
58 {
59 if (w==1) Add(One[u],Zero[v]),Add(Zero[u],One[v]),Add(Zero[v],One[u]),Add(One[v],Zero[u]);
60 if (w==0) Add(One[u],One[v]),Add(One[v],One[u]),Add(Zero[u],Zero[v]),Add(Zero[v],Zero[u]);
61 }
62 }
63
64 for (int i=0;i<n<<1;i++) if (Dfn[i]==-1) Tarjan(i);
65 puts(Check()?"YES":"NO");
66 return 0;
67 }
POJ 3578
1 #include <cstdio>
2 #include <iostream>
3 #include <cstring>
4 #include <algorithm>
5 using namespace std;
6 const int Maxm=80100;
7 int Stk[Maxm],Low[Maxm],Dfn[Maxm],head[Maxm],Belong[Maxm],In[Maxm],Out[Maxm],Pos[Maxm];
8 int cnt,top,Stamp,KASE,scc,n,m,x,u[Maxm],v[Maxm],tot;
9 bool vis[Maxm];
10 struct EDGE{int to,next;}edge[Maxm<<4];
11 inline int Min(int x,int y) {return x>y?y:x;}
12 inline void Swap(int &x,int &y) {int t=x;x=y;y=t;}
13 inline void Add(int u,int v) {edge[cnt].to=v;edge[cnt].next=head[u];head[u]=cnt++;}
14 inline bool Check()
15 {
16 for (int i=1;i<=m;i++) if (Belong[In[i]]==Belong[Out[i]]) return false;
17 return true;
18 }
19 void Tarjan(int u)
20 {
21 Stk[++top]=u; vis[u]=true;
22 Low[u]=Dfn[u]=++Stamp;
23 for (int i=head[u];i!=-1;i=edge[i].next)
24 if (Dfn[edge[i].to]==-1) Tarjan(edge[i].to),Low[u]=Min(Low[u],Low[edge[i].to]); else
25 if (vis[edge[i].to]) Low[u]=Min(Low[u],Dfn[edge[i].to]);
26 if (Low[u]==Dfn[u])
27 {
28 while (true)
29 {
30 int v=Stk[top--];
31 vis[v]=false;
32 Belong[v]=scc;
33 if (u==v) break;
34 }
35 scc++;
36 }
37 }
38 int main()
39 {
40 scanf("%d",&KASE);
41 for (int Kase=1;Kase<=KASE;Kase++)
42 {
43 scanf("%d%d",&n,&m);
44 for (int i=1;i<=m;i++) scanf("%d%d",&u[i],&v[i]);
45 for (int i=1;i<=n;i++) scanf("%d",&x),Pos[x]=i;
46 if(m>3*n-6){puts("NO");continue;}
47 for (int i=0;i<m;i++) In[i+1]=i<<1,Out[i+1]=i<<1|1;
48 tot=0;
49 for (int i=1;i<=m;i++)
50 {
51 u[i]=Pos[u[i]],v[i]=Pos[v[i]];
52 if (v[i]<u[i]) Swap(u[i],v[i]);
53 if ((v[i]-u[i]==1) || (v[i]==n && u[i]==1)) continue;
54 u[++tot]=u[i],v[tot]=v[i];
55 }
56 m=tot;
57 memset(Dfn,-1,sizeof(Dfn));
58 memset(head,-1,sizeof(head));
59 memset(vis,false,sizeof(vis));
60 Stamp=cnt=top=scc=0;
61
62 for (int i=1;i<=m;i++)
63 for (int j=i+1;j<=m;j++)
64 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])))
65 Add(In[i],Out[j]),Add(In[j],Out[i]),Add(Out[i],In[j]),Add(Out[j],In[i]);
66
67 for (int i=0;i<m<<1;i++) if (Dfn[i]==-1) Tarjan(i);
68 puts(Check()?"YES":"NO");
69 }
70 return 0;
71 }
72
BZOJ 1997
时间： 2024-08-17 23:49:07