BZOJ 1997: [Hnoi2010]Planar [2-SAT]

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
using namespace std;
const int N=2005,M=1e6+5,NN=1e4+5;
typedef long long ll;
inline int read(){
    char c=getchar();int x=0,f=1;
    while(c<‘0‘||c>‘9‘){if(c==‘-‘)f=-1;c=getchar();}
    while(c>=‘0‘&&c<=‘9‘){x=x*10+c-‘0‘;c=getchar();}
    return x*f;
}
int n,m,v[N];
struct Node{
    int a,b;
}p[NN];
int tot;
struct edge{
    int v,ne;
}e[M];
int h[N],cnt=0;
inline void ins(int u,int v){
    cnt++;
    e[cnt].v=v;e[cnt].ne=h[u];h[u]=cnt;
}
inline bool isIn(int i,int j){
    return (p[i].a<p[j].a&&p[j].a<p[i].b&&p[i].b<p[j].b)||(p[j].a<p[i].a&&p[i].a<p[j].b&&p[j].b<p[i].b);
}
void buildGraph(){
    for(int i=1;i<=m;i++)
        for(int j=1;j<=m;j++) if(isIn(i,j)){
            int x=i<<1,y=j<<1;
            ins(x-1,y);ins(x,y-1);
            ins(y-1,x);ins(y,x-1);
        }
}
int dfn[N],low[N],dfc,belong[N],scc;
int st[N],top;
void dfs(int u){
    dfn[u]=low[u]=++dfc;
    st[++top]=u;
    for(int i=h[u];i;i=e[i].ne){
        int v=e[i].v;
        if(!dfn[v]){
            dfs(v);
            low[u]=min(low[u],low[v]);
        }else if(!belong[v])
            low[u]=min(low[u],dfn[v]);
    }
    if(dfn[u]==low[u]){
        scc++;int x=0;
        while(x!=u){
            x=st[top--];
            belong[x]=scc;
        }
    }
}
bool judge(){
    for(int i=1;i<=m;i++) if(belong[(i<<1)-1]==belong[i<<1]) return false;
    return true;
}
int main(){
    freopen("in","r",stdin);
    int T=read();
    while(T--){
        cnt=0;memset(h,0,sizeof(h));
        n=read();m=read();
        for(int i=1;i<=m;i++) p[i].a=read(),p[i].b=read();
        for(int i=1;i<=n;i++) v[read()]=i;
        if(m>3*n-6) {puts("NO");continue;}
        tot=0;
        for(int i=1;i<=m;i++){
            p[i].a=v[p[i].a],p[i].b=v[p[i].b];
            if(p[i].a>p[i].b) swap(p[i].a,p[i].b);
            if(p[i].b-p[i].a!=1&&(p[i].a!=1||p[i].b!=n)) p[++tot]=p[i];
        }
        m=tot;
        buildGraph();
        int _=m<<1;
        for(int i=1;i<=_;i++) dfn[i]=low[i]=belong[i]=0;
        for(int i=1;i<=_;i++) if(!dfn[i]) dfs(i);
        if(judge()) puts("YES");
        else puts("NO");
    }
}